The meeting between the United States' Lloyd Austin and China's Dong Jun on the sidelines of the Shangri-La Dialogue is the first substantive face-to-face talks between the two countries' defence chiefs in 18 months.

Dong and Austin began the talks shortly before 1:00 pm (0500 GMT) at the luxury hotel hosting the security forum, a member of the US delegation told reporters.

Defence chiefs and officials from around the world are attending the annual forum that has in recent years become a barometer of US-China relations.

This year's edition comes a week after China held military drills around Taiwan and warned of war over the US-backed island following the inauguration of President Lai Ching-te, who Beijing has described as a "dangerous separatist".

The dispute over democratic Taiwan, which Beijing considers part of its territory, tops the list of disputes between the rivals.

Beijing is also furious over Washington's deepening defence ties in the Asia-Pacific, particularly with the Philippines, and its regular deployment of warships and fighter jets in the Taiwan Strait and South China Sea.

China views this as part of a decades-long US effort to contain it.

President Joe Biden's administration and China have been stepping up communication to ease friction between the nuclear-armed rivals, with Secretary of State Antony Blinken visiting Beijing and Shanghai last month.

A key focus has been the resumption of military-to-military dialogue.

China scrapped military communications with the United States in 2022 in response to then-US House Speaker Nancy Pelosi's visit to Taiwan.

Tensions between Washington and Beijing were stoked further during 2023 by issues including an alleged Chinese spy balloon that was shot down over US airspace, a meeting between Taiwan's then-president Tsai Ing-wen and Pelosi's successor Kevin McCarthy, and American military aid for Taipei.

The two sides agreed after a summit between Chinese leader Xi Jinping and Biden in November last year to restart high-level military talks.

- Pressure points -

That includes a communications channel between the US Indo-Pacific Command chief and Chinese commanders responsible for military operations near Taiwan, Japan and in the South China Sea.

Chinese and American forces have had a series of close encounters in the disputed waterway that China claims almost entirely.

Austin warned prior to Biden and Xi agreeing to resume military-to-military dialogue that accidents have the potential to spiral out of control, especially in the absence of open lines of communication between American and Chinese forces.

Friday's meeting between Austin and Dong follows a phone call between the pair in April, and offers hope of further military talks to cool tensions.

Austin and Dong will give speeches this weekend at the Shangri-La Dialogue in which they are expected to touch on a range of their nations' pressure points.

The United States, increasingly worried about China's fast-developing military capabilities, has been strengthening its alliances and partnerships in the region to counter China's growing assertiveness over Taiwan and in the South China Sea.

In a post on X early Friday announcing his arrival in Singapore, Austin said he would meet with regional counterparts and continue his department's work with "like-minded Indo-Pacific partners to promote our shared vision for a free and open region".

Philippine President Ferdinand Marcos, who has sought to deepen defence cooperation with the United States as he stands up to Chinese actions in waters off the Southeast Asia country, will deliver the Shangri-La Dialogue's keynote speech on Friday.