The relationship between the two countries has deteriorated due to myriad issues in recent years. As well as Taiwan and the South China Sea, they have clashed over cybersecurity and human rights in Hong Kong and Xinjiang.

US Defence Secretary Lloyd Austin met his Chinese counterpart Wei Fenghe on the sidelines of the Shangri-La Dialogue summit, which brings together security officials from around the world, for around an hour.

Austin is the latest senior US official to visit Asia as Washington seeks to shift its foreign policy focus back to the region from the Ukraine war.

Wei told reporters the talks were "honest and sincere" and went "smoothly". Austin tweeted they had "discussed (US-China) defense relations, as well as global and regional security issues".

The pair had previously only held discussions on the phone in April.

Further details on the talks were not released. But a major issue on the agenda may have been Taiwan, a self-ruled, democratic island that lives under the constant threat of invasion by China.

Beijing views the island as its territory and has vowed to one day seize it, by force if necessary.

Tensions have been stoked by the ramp-up in Chinese aircraft incursions into the island's air defence identification zone (ADIZ).

US President Joe Biden, during a visit to Japan last month, appeared to break decades of US policy when, in response to a question, he said Washington would defend Taiwan militarily if it is attacked by China.

The White House has since insisted its policy of "strategic ambiguity" over whether or not it would intervene has not changed.

- Troubled waters -

The two sides have also been at loggerheads over Russia's invasion of Ukraine, with Washington accusing Beijing of providing tacit support for Moscow.

China has called for talks to end the war, but has stopped short of condemning Russia's actions and has repeatedly criticised American arms donations to Ukraine.

In their April phone call, Wei told Austin not to use the invasion to "smear, frame, threaten or pressure China".

China's expansive claims in the South China Sea have also stoked tensions with Washington.

Beijing claims almost all of the resource-rich sea, through which trillions of dollars in shipping trade passes annually, with competing claims from Brunei, Malaysia, the Philippines, Taiwan and Vietnam.

Austin arrived in Singapore late Thursday, and held a series of meetings with his counterparts on Friday.

At a meeting with Southeast Asian defence ministers, he spoke about Washington's "strategy in maintaining an open, inclusive and rules-based regional security environment", according to a statement from the Singapore government.

His comments were a veiled reference to countering China's increasing assertiveness in the region.

Wei meanwhile visited Singapore Prime Minister Lee Hsien Loong, and the pair reaffirmed their countries' "long-standing, warm and friendly bilateral defence relations", according to a statement from Singapore officials.

Austin will deliver a speech at the forum on Saturday, followed by Wei on Sunday. The summit runs from June 10 to 12 and is taking place for the first time since 2019 after twice being postponed due to the Covid-19 pandemic.