The Tribute In Light shines above the skyline of lower Manhattan on the eve of the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in New York City, as seen from Jersey City, New Jersey, U.S., September 10, 2020. REUTERS/Mike Segar TPX IMAGES OF THE DAY

New York City Fire Department (FDNY) firefighters salute outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

Democratic presidential candidate and former Vice President Joe Biden attends the 19th anniversary of the 9/11 attacks with his wife Jill Biden and New York Governor Andrew Cuomo at the National September 11 Memorial & Museum in New York City, New York, U.S., September 11, 2020. Amr Alfiky/Pool via REUTERS

New York City Fire Department (FDNY) firefighters observe moment of silence outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

U.S. President Donald Trump and first lady Melania Trump observe a moment of silence while aboard Air Force One while en route to participate in 19th annual September 11 observance at the Flight 93 National Memorial in Stoystown, Pennsylvania, September 11, 2020. REUTERS/Jonathan Ernst

Democratic presidential candidate and former Vice President Joe Biden attends the 19th anniversary of the 9/11 attacks with his wife Jill Biden and New York Governor Andrew Cuomo at the National September 11 Memorial & Museum in New York City, New York, U.S., September 11, 2020. Amr Alfiky/Pool via REUTERS

U.S. Vice President Mike Pence elbow bumps Jill Biden in greeting as her husband, Democratic presidential nominee and former Vice President Joe Biden, looks on during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

Democratic presidential candidate and former Vice President Joe Biden attends the 19th anniversary of the 9/11 attacks with his wife Jill Biden and New York Governor Andrew Cuomo at the National September 11 Memorial & Museum in New York City, New York, U.S., September 11, 2020. Amr Alfiky/Pool via REUTERS

U.S. President Donald Trump exits Air Force One as he arrives at John Murtha Johnstown-Cambria County Airport in Johnstown, Pennsylvania, September 11, 2020. REUTERS/Jonathan Ernst

A New York City Fire Department (FDNY) firefighter stands in formation with other members outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

U.S. President Donald Trump exits Air Force One as he arrives at John Murtha Johnstown-Cambria County Airport in Johnstown, Pennsylvania, September 11, 2020. REUTERS/Jonathan Ernst

A New York City Police Department (NYPD) officer salutes at ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

Democratic presidential nominee and former U.S. Vice President Joe Biden speaks with U.S. Senator Charles Schumer (D-NY) and New York State Attorney General Letitia James as they attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

U.S. Vice President Mike Pence looks at Democratic presidential nominee and former Vice President Joe Biden as they attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

Democratic presidential nominee and former U.S. Vice President Joe Biden stands with his wife Jill Biden during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

Democratic U.S. presidential nominee Joe Biden walks next to U.S. Senate Minority Leader Chuck Schumer (D-NY) and New York Governor Andrew Cuomo wearing face masks, on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center, at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S. September 11, 2020. REUTERS/Leah Millis

U.S. Vice President Mike Pence wears a protective face mask because of the coronavirus disease (COVID-19) pandemic as he attends ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

Democratic presidential nominee and former U.S. Vice President Joe Biden stands with his wife Jill Biden during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

U.S. Democratic presidential nominee and former Vice President Joe Biden holds his hand over his heart, with his wife Jill Biden at his side, while attending ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

Democratic U.S. presidential nominee Joe Biden and U.S. Senate Minority Leader Chuck Schumer (D-NY) greet eachother with a fist bump during a visit on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S. September 11, 2020. REUTERS/Leah Millis

New York City Fire Department (FDNY) firefighters salute outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

U.S. Secret Service counter assault team snipers stand guard as Air Force Two arrives at LaGuardia airport with Vice President Mike Pence on his way to attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

Democratic U.S. presidential nominee Joe Biden walks next to U.S. Senate Minority Leader Chuck Schumer (D-NY) and New York Governor Andrew Cuomo wearing face masks, during the 19th anniversary of the September 11, 2001 attacks on the World Trade Center, at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S. September 11, 2020. REUTERS/Leah Millis

U.S. Secret Service counter assualt team snipers stand guard as Air Force Two arrives at LaGuardia airport with Vice President Mike Pence on his way to attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

A New York City Fire Department (FDNY) member salutes during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Andrew Kelly

U.S. Vice President Mike Pence arrives at LaGuardia airport with his wife Karen on their way to attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

Union Iron workers gather near the World Trade Center site on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

A U.S. military member adjusts an American flag and flowers during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

Family members attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

New York City Fire Department (FDNY) firefighters gather at Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

New York City Fire Department (FDNY) firefighters gather outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

A New York City Fire Department (FDNY) firefighter stands at attention outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

A woman holds flowers as she arrives to attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

New York City Fire Department (FDNY) firefighters stand at attention outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

A color guard carries American flags as they attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Andrew Kelly

The U.S. flag is unfurled at sunrise as part of the 19th annual September 11 observance ceremony at the Pentagon in Arlington, Virginia, U.S., September 11, 2020. REUTERS/Erin Scott

The U.S. flag is unfurled at sunrise as part of the 19th annual September 11 observance ceremony at the Pentagon in Arlington, Virginia, U.S., September 11, 2020. REUTERS/Erin Scott

The U.S. flag is unfurled at sunrise as part of the 19th annual September 11 observance ceremony at the Pentagon in Arlington, Virginia, U.S., September 11, 2020. REUTERS/Erin Scott

The U.S. flag is unfurled at sunrise as part of the 19th annual September 11 observance ceremony at the Pentagon in Arlington, Virginia, U.S., September 11, 2020. REUTERS/Erin Scott

Democratic presidential candidate and former U.S. Vice President Joe Biden and Vice President Mike Pence greet each other during the 19th anniversary of the 9/11 attacks at the National September 11 Memorial & Museum in New York City, New York, U.S., September 11, 2020. Amr Alfiky/Pool via REUTERS TPX IMAGES OF THE DAY

New York City firefighters salute U.S. Vice President Mike Pence as he stops to visit them outside the Engine 10 and Ladder 10 NYFD fire house after attending ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

A woman places her hand on names of victims at the edge of the North pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

People hug as they sit on a bench at the south refection pool during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

Family members of victims sits along the edge of the South pool during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

People place flowers on the names of victims at the edge of the South pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

A woman pauses at the edge of the South pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

Candian flags are seen left in the name of victim Kenneth William Basnicki at the edge of the North pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

Uniformed U.S. Secret Service officers pause at the edge of the North pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

Flowers and American flags are seen left in the names of victims at the edge of the North pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

New York City Fire Department (FDNY) members stand at the edge of the North pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

A girl places a flower on the edge of the North pool during ceremonies on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Carlo Allegri

New York City Fire Department (FDNY) firefighters stand in formation outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton TPX IMAGES OF THE DAY

People embrace during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Andrew Kelly TPX IMAGES OF THE DAY

New York City Fire Department (FDNY) firefighters salute outside Ladder Co. 10, Engine Co. 10 on the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Shannon Stapleton

U.S. President Donald Trump and first lady Melania Trump stand with White House Press Secretary Kayleigh McEnany, White House Chief of Staff Mark Meadows and Transportation Secretary Elaine Chao as they pause for a moment of silence aboard Air Force One while en route to participate in the 19th annual September 11 observance at the Flight 93 National Memorial in Stoystown, Pennsylvania, September 11, 2020. REUTERS/Jonathan Ernst

The U.S. flag is unfurled at sunrise as part of the 19th annual September 11 observance ceremony at the Pentagon in Arlington, Virginia, U.S., September 11, 2020. REUTERS/Erin Scott

People embrace as they attend ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Andrew Kelly

Democratic presidential nominee and former Vice President Joe Biden holds his hand over his heart as he stands with his wife Jill Biden and U.S. Senate Minority leader Senator Chuck Schumer (D-NY) while attending ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

U.S. Vice President Mike Pence elbow bumps Jill Biden in greeting as her husband, Democratic presidential nominee and former Vice President Joe Biden, looks on during ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center at the 911 Memorial & Museum in New York City, New York, U.S., September 11, 2020. REUTERS/Eduardo Munoz

Former New York City Mayor Rudolph Giuliani attends ceremonies marking the 19th anniversary of the September 11, 2001 attacks on the World Trade Center in the Manhattan borough of New York City, New York, U.S., September 11, 2020. REUTERS/Andrew Kelly