An international security forum has begun in Beijing, and a delegation of the US Defense Department is expected to take part. It comes as dialogue between Chinese and US defense officials has been stalled.

The Beijing Xiangshan Forum got underway on Sunday. The three-day event is organized by groups related to the Chinse military.

Defense ministers, officials and experts from more than 90 countries and international organizations, including the United States and Russia, are scheduled to attend the gathering.

Sunday's sessions included speeches by military experts from China and other countries.

Ahead of the forum, two vice chairpersons of China's Central Military Commission, Zhang Youxia and He Weidong, met the defense ministers of Vietnam and Mongolia.

The two top officers are believed to be in charge of military diplomacy following last week's dismissal of Defense Minister Li Shangfu.

With no replacement named, either of the officers could deliver a speech at the opening ceremony on Monday.

Military-to-military dialogue between China and the United States has been stalled due to Beijing's opposition to Washington's sanctions against Li over weapons purchases from Russia.

The two countries recently traded accusations over each other's military behavior around the South China Sea.

The US accused a Chinese fighter jet of conducting an unsafe intercept of a US bomber. China blamed a US destroyer for crossing the bow of a Chinese destroyer near a group of islands it claims.

Analysts are watching to see whether defense officials of the countries will have some kind of contact at the forum.