Secretary of Defense Lloyd Austin met Thursday with his counterparts from Australia, Japan and the Philippines as the U.S. deepens ties with an emerging regional group that Pentagon officials have privately nicknamed, the “Squad.”

The quadrilateral grouping is one of a number of regional partnerships that Washington has used to push back against China’s assertiveness in Asia. There is also the “Quad” comprised of the U.S., Australia, India and Japan and “Aukus,” a defense pact among Australia, the U.K. and the U.S.

“We’ve gathered here because we share a vision for peace, stability and deterrence in the Indo-Pacific,” Austin said during a joint press briefing in Hawaii with his three counterparts. “We’ve chartered an ambitious course to advance that vision together.”

The defense chiefs of the “Squad” for the first time in June 2023 on the sidelines of the Shangri-La security dialogue in Singapore.

In April, the four nations conducted joint maritime within the Philippines’ exclusive economic zone against the backdrop of ongoing tensions between Manila and Beijing over territorial claims in the South China Sea. Speaking after the talks on Friday, Austin announced the four-country group would look at undertaking more maritime exercises, as well as providing greater security assistance to the Philippines.

Austin said the U.S. had been clear to all nations, including China, that the recent behavior in the South China Sea was “irresponsible” and “disregards international law.”

China views the U.S.’s multilateral groupings as part of Washington’s attempts to contain China. A story in the state-run Global Times this week that the grouping risked “exacerbating regional risks.”

A U.S. official who requested anonymity to discuss the “Squad” said the grouping aims to counter coercion and aggression across Asia, as well as to ensure that defense capabilities among their militaries are increasingly inter-operable, allowing them to work more efficiently together in the event of conflict.

The official said the quadrilateral group aims to conduct more joint patrols in the coming months and years and that these patrols will add more capabilities over time.