US Defense Secretary Lloyd Austin spoke with his Chinese counterpart Dong Jun via video teleconference Tuesday, in the first substantive talks between the superpowers' defense chiefs in nearly 18 months.

The United States has been working to strengthen defense cooperation with its allies in the Asia-Pacific region to counter China's growing influence but also wants to maintain lines of communication with Beijing to prevent tensions from spiraling out of control.

"The two officials discussed US-PRC defense relations and regional and global security issues," the Pentagon said in a statement, referring to the People's Republic of China.

"Secretary Austin emphasized the importance of continuing to open lines of military-to-military communication between the United States and the PRC" following talks between the two sides in recent months, the statement said.

Austin also "reiterated that the United States will continue to fly, sail, and operate -- safely and responsibly -- wherever international law allows," and "underscored the importance of respect for high seas freedom of navigation guaranteed under international law, especially in the South China Sea."

Beijing, in turn, said Dong had used the talks to call for greater "trust" between the two powers.

"China and the United States should... take peace as the most precious, stability as the most important," Dong told Austin, according to a Beijing readout.

"The military sphere is the key... to stabilizing the development of the relationship and preventing major crises from occurring," Dong said.

But he also warned the US over the self-ruled island of Taiwan, which Beijing claims as its own.

"Dong Jun emphasized that the Taiwan issue is the core of China's core interests," the defence ministry readout said.

He also urged the US to respect his country's position on the South China Sea, which Beijing claims almost in its entirety and where tensions have flared in recent months.

"The US side should recognize China's firm position, respect China's territorial sovereignty and maritime rights and interests in the South China Sea, and take practical actions to safeguard regional peace," Dong said.

Austin's last significant interaction with a Chinese counterpart occurred in November 2022 when he met with Wei Fenghe in Cambodia.

Wei was subsequently replaced by Li Shangfu, who shook hands and spoke briefly with Austin at a defense conference in Singapore last June but did not hold a formal meeting with the Pentagon chief.

China was unwilling to agree to talks between Austin and Li while the latter was under American sanctions, a senior US defense official told journalists -- an obstacle that was removed when Li was replaced by Dong last year.

- US-China tensions -

There are multiple points of contention between Washington and Beijing, especially over Taiwan, the democratic, self-ruled island, which China claims as part of its territory and has said it will not rule out using force to bring under its control.

Beijing halted cooperation with the United States on issues including defense talks in August 2022 to express its displeasure over a visit by then-US House speaker Nancy Pelosi to the island, but US President Joe Biden and his Chinese counterpart Xi Jinping agreed at a summit in November to the resume discussions.

Disputes over the South China Sea -- which Beijing claims almost in its entirety -- is another potential flashpoint, with clashes between Chinese and Philippine vessels stoking fears of wider conflict.

The United States has also highlighted multiple incidents in recent years in which it says Chinese warplanes and ships have operated in an unsafe manner around American aircraft and vessels.

Austin has repeatedly emphasized the importance of military-to-military communications as a means of heading off possible conflict, and there have been several recent interactions between military officials from the United States and China despite tensions between the two sides.

These include top US military officer General Charles "CQ" Brown speaking with his counterpart General Liu Zhenli in December, and talks between military officials from Washington and Beijing this month on safety in interactions between their armed forces.

The Pentagon and China "are continuing to discuss future engagements between our senior defense and military leaders," the senior US defense official said, adding: "These engagements provide us with opportunities to prevent competition from veering into conflict by speaking candidly about our concerns."