Tens of thousands of people attend an annual candlelight vigil at the Victoria Park in Hong Kong, China June 4, 2015 to mark Beijing's Tiananmen Square crackdown in 1989, as tension lingers in the financial hub from its pro-democracy protests last year. REUTERS/Tyrone Siu TPX IMAGES OF THE DAY

People hold candles during a candlelight vigil to commemorate the 25th anniversary of the June 4 Tiananmen Square incident, in Kuala Lumpur June 4, 2014. China deployed its vast security apparatus on Wednesday to snuff out commemoration of the suppression of pro-democracy protests around Tiananmen Square 25 years ago, flooding the streets with police as censors scrubbed the Internet clean of any mention of the crackdown. REUTERS/Samsul Said (MALAYSIA - Tags: ANNIVERSARY CIVIL UNREST POLITICS) 

Tens of thousands of people participate in a candlelight vigil at Hong Kong's Victoria Park June 4, 2014, to mark the 25th anniversary of the military crackdown of the pro-democracy movement at Beijing's Tiananmen Square in 1989. REUTERS/Paul Yeung (CHINA - Tags: ANNIVERSARY CIVIL UNREST POLITICS TPX IMAGES OF THE DAY) 

A student takes part in a 64-hour hunger strike in in Hong Kong's Times Square June 3, 2012. Monday marks the 23rd anniversary of the military crackdown of the movement. The Chinese characters on the slogan read: "Hunger strike". REUTERS/Tyrone Siu (CHINA - Tags: POLITICS SOCIETY) 

Student protesters pose for pictures in front of an installation depicting the 1989 pro-democracy movement at Beijing's Tiananmen Square, at Hong Kong's Victoria Park June 3, 2012. Monday marks the 23rd anniversary of the military crackdown of the movement. REUTERS/Tyrone Siu (CHINA - Tags: POLITICS SOCIETY CIVIL UNREST) 

Pro-democracy leaders sing on the podium during a candlelight vigil at Hong Kong's Victoria Park June 4, 2011, to mark the 22nd anniversary of the military crackdown of the pro-democracy movement at Beijing's Tiananmen Square in 1989. The Chinese characters on the backdrop reads: "Redress the miscarriage of justice on June 4th. Build democracy". REUTERS/Bobby Yip (CHINA - Tags: POLITICS ANNIVERSARY CIVIL UNREST) 

Tens of thousands of protesters take part in a candlelight vigil at Hong Kong's Victoria Park June 4, 2011 to mark the 22nd anniversary of the military crackdown of the pro-democracy movement at Beijing's Tiananmen Square in 1989. REUTERS/Bobby Yip (CHINA - Tags: POLITICS ANNIVERSARY CIVIL UNREST) 

A protester holds a candle during a candlelight vigil at Hong Kong's Victoria Park June 4, 2010 to mark the 21st anniversary of the military crackdown on the pro-democracy movement at Beijing's Tiananmen Square in 1989. REUTERS/Bobby Yip (CHINA - Tags: POLITICS CIVIL UNREST) 

Protesters take part in a candlelight vigil at Hong Kong's Victoria Park June 4, 2010 to mark the 21st anniversary of the military crackdown on the pro-democracy movement at Beijing's Tiananmen Square in 1989. REUTERS/Bobby Yip (CHINA - Tags: POLITICS) 

CHINA-TIANANMEN - 3d diagram of the Tiananmen Square, with pointers to key structures, and timeline leading up to the protests and the June Fourth Incident 21 years ago. RNGS. (SIN01) 

Activists gather during a candlelight vigil at Hong Kong's Victoria Park June 4, 2009 to mark the 20th anniversary of the crackdown on the pro-democracy movement in Beijing's Tiananmen Square in 1989. Cradling candles, laying wreaths and clad in black or white, Hong Kong residents transformed a downtown park into a speckled sea of flickering lights, in remembrance of the hundreds of pro-democracy demonstrators and students crushed by tanks and troops near the square two decades ago. REUTERS/Aaron Tam (CHINA POLITICS ANNIVERSARY IMAGES OF THE DAY) 

Activists gather during a candlelight vigil at Hong Kong's Victoria Park June 4, 2009 to mark the 20th anniversary of the crackdown on the pro-democracy movement in Beijing's Tiananmen Square in 1989. Cradling candles, laying wreaths and clad in black or white, Hong Kong residents transformed a downtown park into a speckled sea of flickering lights, in remembrance of the hundreds of pro-democracy demonstrators and students crushed by tanks and troops near the square two decades ago. REUTERS/Tyrone Siu (CHINA POLITICS ANNIVERSARY CONFLICT) 

Tens of thousands of people take part in a candlelight vigil at Hong Kong's Victoria Park June 4, 2009 to mark the 20th anniversary of the crackdown on the pro-democracy movement in Beijing's Tiananmen Square in 1989. Cradling candles, laying wreaths and clad in black or white, Hong Kong residents transformed a downtown park into a speckled sea of flickering lights, in remembrance of the hundreds of pro-democracy demonstrators and students crushed by tanks and troops near the square two decades ago. REUTERS/Tyrone Siu (CHINA POLITICS CONFLICT ANNIVERSARY) 

People walk past a statue of the Goddess of Democracy during a candlelight vigil at Hong Kong's Victoria Park June 4, 2009 to mark the 20th anniversary of the crackdown on the pro-democracy movement in Beijing's Tiananmen Square in 1989. Cradling candles, laying wreaths and clad in black or white, Hong Kong residents transformed a downtown park into a speckled sea of flickering lights, in remembrance of the hundreds of pro-democracy demonstrators and students crushed by tanks and troops near the square two decades ago. REUTERS/Tyrone Siu (CHINA POLITICS ANNIVERSARY CONFLICT IMAGES OF THE DAY) 

A screen displays an image of the late former Chinese Premier Zhao Ziyang speaking to students in 1989 as tens of thousands of people take part in a candlelight vigil at Hong Kong's Victoria Park June 4, 2009 to mark the 20th anniversary of the crackdown on the pro-democracy movement in Beijing's Tiananmen Square in 1989. REUTERS/Bobby Yip (CHINA POLITICS CONFLICT ANNIVERSARY) 

Tens of thousands of people take part in a candlelight vigil at Hong Kong's Victoria Park June 4, 2009, to mark the 20th anniversary of the crackdown on the pro-democracy movement in Beijing's Tiananmen Square in 1989. REUTERS/Bobby Yip (CHINA POLITICS CONFLICT ANNIVERSARY CITYSCAPE) 

Thousands of people take part in a candlelight vigil at Hong Kong's Victoria Park June 4, 2009 to mark the 20th anniversary of the crackdown on the pro-democracy movement in Beijing's Tiananmen Square in 1989. REUTERS/Bobby Yip (CHINA POLITICS CONFLICT ANNIVERSARY IMAGES OF THE DAY) 

A man walks past a banner, printed with a photo of a man standing in front of tanks during the 1989 military crackdown on pro-democracy protesters around Beijing's Tiananmen Square, at Hong Kong's Victoria Park June 4, 2009. Tens of thousands of people are expected to attend a candlelight vigil later in the evening to commemorate those who died in the crackdown. REUTERS/Tyrone Siu (CHINA ANNIVERSARY CONFLICT POLITICS) 

A man stands passively to block a column of army tanks on Changan Avenue east of Tiananmen Square in Beijing in this June 5, 1989 file photo.The tanks did not slow down, but they did turn around him before taking up position in another part of the city. Tanks rolled into the square before dawn on June 4, 1989, to crush a pro-democracy movement. The ruling Communist Party has never released a death toll and fears any public marking of the crackdown could undermine its hold on power. REUTERS/Arthur Tsang/Files (CHINA ANNIVERSARY CONFLICT MILITARY POLITICS) 

Combination photo shows (top) a man blocking a column of army tanks on Changan Avenue east of Tiananmen Square in Beijing June 5, 1989 and the same section filled with traffic June 4, 2009. Tanks rolled into the square before dawn on June 4, 1989, to crush a pro-democracy movement. The ruling Communist Party has never released a death toll and fears any public marking of the crackdown could undermine its hold on power. REUTERS/Arthur Tsang/David Gray (CHINA ANNIVERSARY CONFLICT POLITICS IMAGES OF THE DAY) 

Flowers are laid on the "Pillar of Shame -- A memorial for Tiananmen" by Danish artist Jens Galschiot, during a candlelight vigil at the University of Hong Kong June 3, 2009, one day before the 20th anniversary of the June 4 military crackdown on the pro-democracy movement in Beijing's Tiananmen Square. REUTERS/Bobby Yip (CHINA POLITICS ANNIVERSARY) 

Demonstrators in Tiananmen Square continue their protest in front of a defaced protrait of the late Chairman Mao on May 23, 1989. REUTERS/Shunsuke Akatsuka 

Student protesters construct a tent to protect them from the elements on May 26, 1989. The student-led protest in Tiananmen Square is in its 14th day. REUTERS/Shunsuke Akatsuka 

An armoured personel carrier crushes one of the tents set up on Tiananmen Square by pro-democracy protestors early Sunday morning on June 4, 1989. REUTERS/STR 

Pro-democracy demonstrator Leung Kwok Hung stands behind a banner asking Hong Kong's decision makers to recognise those killed in Tiananmen Square as Chinese patriots and not counter-revolutionary subversives outside the Legislative Council (Legco) building in Hong Kong May 21. The demonstrators handed to Legco members copies of a local pro-China newspaper dated June 5, 1989, which at the time condemned the brutal crackdown. The placard reads "Redress June 4 Massacre".

HONGKONG TIANANMEN 

A man wipes tears as he joins tens of thousands of people participate in a candle vigil at Hong Kong's Victoria Park June 4 to mourn pro-democracy activists killed by China's army 10 years ago around Beijing's Tiananmen Square. Hundreds of people died when Beijing sent in tanks to quell the pro-democracy demonstrations on June 4, 1989.
??» 

A woman attends an exhibition at the Taipei City Hall on June 3 to mark the 10th anniversary of the 1989 massacre Tiananmeni Square. The picture shows a Chinese man standing in front of a row of tanks during the June 4 Tiananmen Square crackdown on pro-democracy activists in 1989. A candle-light march, staged by the city government, will be held in the night of June 4 from the city hall to Taipei's Chiang Kai-shek Memorial Hall.

LC/RM 

FILE PHOTO 4JUN89 - A captured tank driver is helped to safety by students as the crowd beats him June 4, 1989. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square. REUTERS/Stringer 

FILE PHOTO 04JUN89 - A blood-covered protestor holds a Chinese soldier's helmet following violent clashes with military forces during the 1989 pro-democracy demonstrations in Beijing's Tiananmen Square. This year marks the 10th anniversary of the bloody June 4 army crackdown in the square. 

Chinese electricains install a surveillance camera May 19 above one of Beijing's main roads, ahead of the sensitive 10th anniversary of China's crackdown on pro-democracy protesters in Tiananmen Square. China has ruled out a re-evaluation of the 1989 crackdown, saying the decision to use military force against unarmed students was "correct." In the early morning of June 4, 1989, Chinese troops crushed a month-long series of demonstrations seeking greater freedoms and attacking government corruption. Hundreds were killed.

NB/CC 

FILE PHOTO 5JUN89 - A Beijing citizen stands in front of tanks on the Avenue of Eternal Peace in this June 5, 1989 file photo during the crushing of the Tiananmen Square uprising. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square. 

FILE PHOTO 5JUN89 - A Beijing citizen stands in front of tanks on the Avenue of Eternal Peace in this June 5, 1989 file photo during the crushing of the Tiananmen Square uprising. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square. 

Chinese President Jiang Zemin waves from his armoured limo after his arrival on the U.S. mainland at Langley Air Force Base on the second stop of his U.S. tour, late October 27. Jiang began the first state visit to the United States by a Chinese leader since the 1989 crackdown on the Tiananmen Square pro-democracy movement.

SUMMIT JIANG ARRIVAL 

Chinese People's Liberation Army soldiers and tanks guard the Gate of heavenly Peace and the portrait of Chairman Mao in Tiananmen Square June 9, 1989. The military occupation of the city continues as thousands of Foreign nationals flee the country. REUTERS/Richard Ellis BEST QUALITY AVAILABLE 

A Beijing citizen stands in front of tanks on the Avenue of Eternal Peace in this June 5, 1989 file photo during the crushing of the Tiananmen Square uprising. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square. REUTERS/Arthur Tsang PP05010072 JIR/LCY 

A Beijing citizen stands in front of tanks on the Avenue of Eternal Peace in this June 5, 1989 file photo during the crushing of the Tiananmen Square uprising. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square. REUTERS/Arthur Tsang

JIR/LCY 

FILE PHOTO 5JUN89 - Qinghua University student Duan Changlong, killed in the 1989 Tiananmen Square army crackdown on pro-democracy demonstrations, is draped in a red flag with Chinese characters "Nationality" during a funeral ceremony on June 5, 1989. June 4 will mark the 10th anniversary of the military crackdown. Picture taken 5JUN89.

ASW/RM 

A man stands in front of a convoy of tanks in the Avenue of Eternal
Peace in Beijing, June 5, 1989. REUTERS/Arthur Tsang

AS 

FILE PHOTO 5JUN89 - A Peking citizen stands passively in front of tanks on the Avenue of Eternal Peace in this June 5, 1989, file photo taken during the crushing of the Tiananmen Square uprising. The tanks did not slow down, but they did turn around him before taking up positions in another part of the city. Chinese leader Deng Xiaoping, whose economic pragmatism transformed China but whose political authoritarianism led to the Tiananmen Square massacre, died February 19 at the age of 93. REUTERS/Arthur Tsang

DENG 

A blood-covered protester holds a Chinese soldier's helmet following violent clashes with military forces during the 1989 pro-democracy demonstrations in Beijing's Tiananmen Square in this June 4, 1989 file photo. REUTERS/Shunsuke Akatsuka (CHINA POLITICS CONFLICT) 

An armoured personel carrier crushes one of the tents set up on Tiananmen Square by pro-democracy protestors early Sunday morning June 4, 1989. Students were later able to set fire to the vehicle before troops entered the square and opened fire. REUTERS/Stringer BEST QUALTY AVAILABLE 

FILE PHOTO 4JUN89 - A captured tank driver is helped to safety by students as the crowd beats him June 4, 1989. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square.

LCY/RM 

FILE PHOTO JUN89 - Chinese student leaders (L-R:) Chai Ling, Wang Dan, Feng Congde and Li Lu swear to remain in Beijing's Tiananmen Square throughout June, 1989. Hundreds of people were killed on June 4, 1989 when Chinese troops crushed month-long pro-democracy demonstrations which attacked government corruption. This year marks the 10th anniversary of the bloody June 4 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square.

LCY/rm 

15TH IN A SERIES OF 16

PEK59:CHINA-TIANANMEN:BEIJING,31MAY99 - FILE PHOTO 4JUN89 - Crowds of jubilant students surge through a police cordon before pouring into Tiananmen Square on June 4, 1989 during a pro-democracy demonstration. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square. REUTERS/Stringer 

FOR RELEASE WITH BC-CHINA-CLINTON-TIANANMEN - FILE PHOTO MAY 89 - Student protesters arriving at Tiananmen Square to join other pro-democracy demonstrators, ride pass the portrait of late chairman Mao Zedong. The demonstrations were crushed by the People's Liberation Army on June 4, 1989. The square, where U.S. President Bill Clinton will visit on July 27, is the heart of China's power centre with a jagged history of revolution and bloodshed. Picture taken MAY 1989.

ASW/TAN/WS 

Pro-democracy demonstrators pitch tents in Beijing's Tiananmen Square before their protests were crushed by the People's Liberation Army on June 3, 1989. The square, where U.S. President Bill Clinton will visit on July 27, is the heart of China's power centre with a jagged history of revolution and bloodshed. REUTERS/Bobby Yip 

FILE PHOTO 30MAY89 - A portrait of China's late chairman, Mao Zedong, overlooks Beijing's Tiananmen Square occupied by pro-democracy protestors and the "Goddess of Democracy" May 30, 1989. This year marks the 10th anniversary of the bloody June 4 1989 army crackdown on the pro-democracy movement at Beijing's Tiananmen Square. REUTERS/Pat Benic

LCY/RM 

Student protesters construct a scaffold at sunset May 29, 1989, which will be used to erect the "Goddess of Democracy" in Tiananmen Square overnight. The statue is modeled aster the USA's Statue of Liberty. REUTERS/Shunsuke Akatsuka BEST QUALITY AVAILABLE 

Student protesters construct a tent to protest them from the elements May 26, 1989. The Gate of Heavenly Peace is in the background. The student-led protest in Tiananmen Square is in its 14th day. REUTERS/Shunsuke Akatsuka BEST QUALITY AVAILABLE 

A chinese protestor holds up a caricature of Premier Li Peng dressed in a Nazi uniform during an anti-government demonstration in Tiananmen Square May 25, 1989. The students are demanding the resignation of Li, who announced martial law six days ago. REUTERS/Ed Nachtrieb BEST QUALTY AVAILABLE 

Workmen try to drape the portrait of Mao Tse-tung in Beijing's Tiananmen Square after it was pelted with paint in this May 23, 1989 file photo. REUTERS/Ed Nachtrieb (CHINA POLITICS CONFLICT) 

A demonstrator gives the victory sign as workmen finish putting a drap over a huge protrait of Chairman Mao on the Gate of Heavenly Peace May 23, 1989. The demonstrators disclaim any responsibility for defacing the protrait. REUTERS/Ed Nachtrieb BEST QUALTY AVAILABLE 

Demonstrators in Tiananmen Square continue their protest in front of a defaced protrait of the late Chairman Mao May 23, 1989. Paint was splattered on the protrait by three people. REUTERS/Shunsuke Akatsuka BEST QUALTY AVAILABLE 

A military helicopter drops leaflets above Tiananmen Square May 22, 1989, which state that the student protesters should leave the Square as soon as possible on Monday morning. On the third day of martial law, the troops have yet to enter central Beijing. REUTERS/Shunsuke Akatsuka BEST QUALITY AVAILABLE