The Beijing Xiangshan Forum, China's biggest annual show of military diplomacy, began on Sunday without the country's defence minister, who typically hosts the event.
"We will deepen strategic co-operation and co-ordination with Russia, and on the basis of mutual respect, peaceful coexistence and win-win co-operation, develop military ties with the US," Zhang Youxia, vice chairman of the Central Military Commission, said during a keynote address at the forum.
China's defence minister has delivered that speech in previous years.
China and the US have had no direct military-to-military communications since the Washington-sanctioned former Chinese defence minister, Li Shangfu, was appointed in March.
Li was sacked last week without explanation, and China did not name a replacement. Reuters reported last month that Li, who has been missing for two months, was being investigated over corruption.
"Some countries deliberately create turbulence and interfere in other countries' internal affairs, and instigate colour revolutions," Zhang said, in a veiled attack at Western countries including the United States, which is increasingly co-ordinating with allies to curtail Beijing's military ambitions.
A colour revolution is a term the Chinese government uses to describe attempts to overthrow Communist Party rule.
Zhang also accused "some countries" of holding on to a zero-sum game mentality and engaging in clique politics.
"Countries should not deliberately provoke other countries on major and sensitive issues such as Taiwan," he said, adding that Taiwan is China's core interests, in comments directed at the US.
The US defence department has sent a delegation led by Cynthia Xanthi Carras, China country director in the Office of the Undersecretary of Defense.
Many Western countries have either shunned the forum or are only sending small and low-level delegations, preferring instead to discuss international security issues at the Shangri-La Dialogue held annually in Singapore.
