China is holding a lavish parade in Beijing to mark the defeat of Japan in World War Two, showcasing its military might on an unprecedented scale.
President Xi Jinping in his opening speech paid tribute to "the Chinese people who unwaveringly fought hard and defeated aggression" from Japan.
He also said the People's Liberation Army would be reduced by 300,000 personnel, but gave no timeframe.
China's growing military power is being keenly watched amid regional tensions.
Some 12,000 troops and 200 aircraft, as well as tanks and missiles, are on display in Tiananmen Square.
More than 80% of the machinery on display is being shown in public for the first time, state media has said.
Mr Xi, who is also commander of the armed forces, is centre stage at the proceedings along with more than 30 foreign government officials and heads of state.
'China will not seek expansion'
Mr Xi made the troop reduction announcement in a speech where he reassured the global community that "China will remain committed to peaceful development".
"No matter how strong it becomes, China will never seek hegemony or expansion. It will never inflict its past suffering on any nation," he said.
BBC China Editor Carrie Gracie, who is watching the parade, says the army cuts will not mean a weaker China.
China is also upgrading its naval and air forces, she says, so does not need as many boots on the ground to project its power around the world.
Alexander Neill from the International Institute for Strategic Studies (IISS) in Singapore, said the move shows China's "determination to have a modern fighting force".
Leaders shun event
China's People's Liberation Army (PLA) is the world's largest military, with 2.3 million members. China also has the second biggest defence budget after the US.
Russian President Vladimir Putin, South Korea's President Park Geun-hye and, controversially, UN Secretary General Ban Ki-moon, are among the biggest names in attendance.
But many major leaders, including from the US, UK, Australia and Japan, have shunned the event.
"During a period of strained relations between China and Japan, as well as increasing military tension in the Asia-Pacific region, some leaders are reluctant to be associated with what they may view as a nationalistic, anti-Japanese mass rally," says Mr Neill.
In the build-up to the event, state media have been publishing commentaries that reinforce Chinese patriotism and views on historical events.
Beijing's normally smoggy skies are unusually blue, after factories were closed, barbecues banned and cars stopped from travelling.
There are no balloons or pigeons around the square in case they disrupt the fly-past of military aircraft, she says.
Japan launched a full-scale invasion of China in 1937 and, according to Beijing, eight years of fighting claimed 14 million Chinese lives.
China also claims that it is the "forgotten ally" and that its role in defeating Japan has been underplayed in the post-war narrative.
Nationalist forces led the fight against Japan in China. They were defeated by Mao Zedong's Communists who proclaimed a people's republic in 1949.
