German Chancellor Angela Merkel makes a speech from behind a bullet proof glass at the Brandenburg Gate in Berlin, June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. President Barack Obama shakes hands with Berlin Mayor Klaus Wowereit (R) behind a bullet proof glass at the Brandenburg Gate in Berlin, June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel sit behind a bullet proof glass before speaking at the Brandenburg Gate in Berlin, June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

A woman hands out bottles of water to invited guest as they wait for the arrival of U.S. President Barack Obama, at Pariser Platz in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Fabrizio Bensch (GERMANY - Tags: POLITICS)

Members of the special police force observe the area below at Parisier Platz as they await the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS CRIME LAW)

Members of the special police force observe the area below at Parisier Platz as they await the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS CRIME LAW)

Invited guests await the arrival of U.S. President Barack Obama in front of the Brandenburg Gate in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Fabrizio Bensch (GERMANY - Tags: POLITICS)

Police marksmen observe the area below at Parisier Platz as they await the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Wolfgang Rattay (GERMANY - Tags: POLITICS CRIME LAW)

Members of the special police force observe the area below at Parisier Platz as they await the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS CRIME LAW)

Invited guests are entertained by violinist David Garrett (background R) as they await the arrival of U.S. President Barack Obama in front of the Brandenburg Gate in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

Invited guests stand at Parisier Platz as they await the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Fabrizio Bensch (GERMANY - Tags: POLITICS)

Members of the special police force shade themselves from the sun under a tarpaulin, as they observe the area below from a roof of a building at Parisier Platz while waiting for the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Fabrizio Bensch (GERMANY - Tags: POLITICS CRIME LAW)

Members of the special police force observe the area below at Parisier Platz as they await the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Fabrizio Bensch (GERMANY - Tags: POLITICS CRIME LAW)

An invited guest shields himself from the sun with his jacket while waiting for the arrival of U.S. President Barack Obama, at Pariser Platz in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Fabrizio Bensch (GERMANY - Tags: POLITICS)

Invited guests stand in a tribune at Parisier Platz as they await the arrival of U.S. President Barack Obama, in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Fabrizio Bensch (GERMANY - Tags: POLITICS)

U.S. President Barack Obama shankes hands with German Chancellor Angela Merkel (L) after a news conference following their meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama smiles next to German Chancellor Angela Merkel (L) after a news conference following their meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS TPX IMAGES OF THE DAY)

U.S. President Barack Obama speaks next to German Chancellor Angela Merkel (R) during a news conference after their meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama gestures as he addresses a news conference after a bilateral meeting with German Chancellor Angela Merkel at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS HEADSHOT)

U.S. President Barack Obama speaks next to German Chancellor Angela Merkel (2nd L) during a news conference after their meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama addresses a news conference after a bilateral meeting with German Chancellor Angela Merkel at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS HEADSHOT)

U.S. President Barack Obama speaks next to German Chancellor Angela Merkel (R) during a news conference after their meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama speaks next to German Chancellor Angela Merkel (R) during a news conference after their meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS TPX IMAGES OF THE DAY)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel (R) make their way to a news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Thomas Peter (GERMANY - Tags: POLITICS)

U.S. President Barack Obama and German Chancellor Angela Merkel arrive for a joint news conference at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Kevin Lamarque (GERMANY - Tags: POLITICS) 

U.S. first lady Michelle Obama (L) and her daughter Sasha place flowers as they visit the Berlin Wall memorial in Bernauer Strasse in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

US first lady Michelle Obama visits the Holocaust Memorial in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/ Joerg Carstensen/Pool (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (L) and her daughters Sasha and Malia (3L) place flowers as they visit the Berlin Wall memorial in Bernauer Strasse with her husband's half sister Auma Obama (4L) and Joachim Sauer, the husband of German Chancellor Angela Merkel, in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (2nd L) her husband's half sister Auma Obama (L) and her daughters Sasha (C) and Malia (R) visit the Holocaust Memorial in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at 2nd R is unidentified. REUTERS/Joerg Carstensen/Pool (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama and her daughters Malia (C) and Sasha (R) visit the Holocaust Memorial in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Joerg Carstensen/Pool (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama's daughters Sasha (R) and Malia visit the Berlin Wall memorial in Bernauer Strasse in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama's daughters Sasha (L) and Malia visit the Berlin Wall memorial in Bernauer Strasse in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (L) and her daughters Sasha and Malia (3L) place flowers as they visit the Berlin Wall memorial in Bernauer Strasse with her husband's half sister Auma Obama (4R) and Joachim Sauer (4L), the husband of German Chancellor Angela Merkel, in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (L) and her daughters Sasha and Malia (3L) place flowers as they visit the Berlin Wall memorial in Bernauer Strasse in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (L) and her daughters Sasha and Malia (3L) place flowers as they visit the Berlin Wall memorial in Bernauer Strasse with her husband's half sister Auma Obama (R) and Joachim Sauer (2R), the husband of German Chancellor Angela Merkel, in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

German Chancellor Angela Merkel, National Security Advisor Thomas Donilon, U.S. President Barack Obama and U.S. Ambassador to Germany Philip Murphy ( L-R) attend a bilateral meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Gero Breloer/Pool (GERMANY - Tags: POLITICS )

German Chancellor Angela Merkel, National Security Advisor Thomas Donilon, U.S. President Barack Obama and U.S. Ambassador to Germany Philip Murphy ( L-R) attend a bilateral meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Gero Breloer/Pool (GERMANY - Tags: POLITICS )

U.S. first lady Michelle Obama (R) watches her daughter Sasha as she places a flower at the Berlin Wall memorial in Bernauer Strasse in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. President Barack Obama, U.S. Ambassador to Germany Philip Murphy, Deputy Chief of Staff Rob Nabors (background L-R) and German Chancellor Angela Merkel (foreground R) attend a bilateral meeting at the Chancellery in Berlin June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Gero Breloer/Pool (GERMANY - Tags: POLITICS )

U.S. first lady Michelle Obama (R) watches her daughter Sasha as she places a flower at the Berlin Wall memorial in Bernauer Strasse in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (R) watches her daughter Sasha as she places a flower at the Berlin Wall memorial in Bernauer Strasse in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (R) visits the Berlin Wall memorial Bernauer Strasse with her husband's half sister Auma Obama (2nd R) her daughters Sasha (L) and Malia (2nd L) and Joachim Sauer (3rd R) the husband of German Chancellor Angela Merkel in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (R) visits the Berlin Wall memorial Bernauer Strasse with her husband's half sister Auma Obama (2nd R) her daughters Sasha (L) and Malia (2nd L) and Joachim Sauer (3rd R) the husband of German Chancellor Angela Merkel in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at centre is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (3rd R) visits the Berlin Wall memorial Bernauer Strasse with her husband's half sister Auma Obama (C) her daughters Sasha (2nd L) and Malia (L) and Joachim Sauer (3rd L) the husband of German Chancellor Angela Merkel in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Men at right are unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

Activists of Amnesty International stage a protest in Berlin's Potsdamer Platz against U.S. military prison at Guantanamo Bay during U.S. President Barack Obama's visit to Berlin, June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Christian Ruettger (GERMANY - Tags: POLITICS CIVIL UNREST)

U.S. first lady Michelle Obama, her husband's half sister Auma Obama (L) and her daughter Malia (R) visit the Holocaust Memorial in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Jens Meyer/Pool (GERMANY - Tags: POLITICS )

Activists of Amnesty International stage a protest in Berlin's Potsdamer Platz against U.S. military prison at Guantanamo Bay during U.S. President Barack Obama's visit to Berlin, June 19, 2013. Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Christian Ruettger (GERMANY - Tags: POLITICS CIVIL UNREST)

U.S. first lady Michelle Obama and her daughters Malia (C) and Sasha (R) visit the Holocaust Memorial in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Jens Meyer/Pool (GERMANY - Tags: POLITICS TPX IMAGES OF THE DAY)

U.S. first lady Michelle Obama and her daughter Malia (R) visit the Holocaust Memorial in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Jens Meyer/Pool (GERMANY - Tags: POLITICS)

US first lady Michelle Obama visits the Holocaust Memorial in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. REUTERS/Jens Meyer/Pool (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (2nd L) visits the Berlin Wall memorial Bernauer Strasse with her husband's half sister Auma Obama (C) her daughter Malia (R) and Joachim Sauer (3rd L) the husband of German Chancellor Angela Merkel, in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at left is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)

U.S. first lady Michelle Obama (2nd L) visits the Berlin Wall memorial Bernauer Strasse with her husband's half sister Auma Obama (2nd R) her daughters Sasha (C) and Malia (R) in Berlin June 19, 2013. U.S. President Barack Obama will unveil plans for a sharp reduction in nuclear warheads in a landmark speech at the Brandenburg Gate on Wednesday that comes 50 years after John F. Kennedy declared "Ich bin ein Berliner" in a defiant Cold War address. Man at left is unidentified. REUTERS/Tobias Schwarz (GERMANY - Tags: POLITICS)