China's defence spending is the second largest in the world after the US, and tensions have dramatically increased between rival powers as Beijing has poured trillions of yuan into the modernisation of its military.

But the country has repeatedly sought to allay fears over its military intentions, projecting itself as a peaceful counterpoint to what it calls the "bullying, hegemonic behaviour" of Washington.

Troops from Thailand, Mongolia and Pakistan joined China's armed forces for the 10-day exercise dubbed "Shared Destiny 2021" at the military base in Queshan county in central Henan province.

Senior Colonel Lu Jianxin told journalists invited to the base that the exercise "demonstrates China's support for the multilateral system centred on the UN" as Beijing sought to put its defence diplomacy on full display.

Blue-helmeted soldiers took turns role-playing various scenarios: civilians and refugees caught up in a brawl, or armed militants attacking UN forces.

Dozens of armoured vehicles, bulldozers, helicopters and tanks -- all bearing the UN logo -- were mobilised for the event.

As of the end of July, China was the eighth-largest contributor to peacekeeping troops, with 2,158 military personnel engaged around the world, according to UN data.

Chinese forces are mainly engaged in South Sudan, Mali, Lebanon and the Democratic Republic of Congo.

During her trip to Asia last month, US Vice President Kamala Harris described China's disputes with its neighbours over the South China Sea as undermining "the rules-based order and threaten[ing] the sovereignty of nations".