US President Joe Biden hailed closer ties with Vietnam on Sunday as the two countries struck a deal to deepen cooperation, including on semiconductors, but said he was not aiming to contain China.

The "comprehensive strategic partnership" with Hanoi is part of Washington's push to bolster its network of allies around Asia and the Pacific in the face of Beijing's rising influence.

Biden accused Beijing of seeking to bend the international order to its will.

"One of the things that is going on now is China is beginning to change some of the rules of the game, in terms of trade and other issues," Biden said.

Sometimes to Beijing's chagrin, Washington has invested heavily in building alliances as part of its Indo-Pacific strategy, including the Quad security dialogue with India, Australia and Japan, and the AUKUS pact with Britain and Australia.

Biden said he wanted establish clear ground rules for relations.

"I don't want to contain China. I just want to make sure we have a relationship with China that is on the up and up, squared away, everybody knows what it's all about," he said.

Biden flew in to Hanoi straight from a G20 summit that failed to agree to a phase-out of fossil fuels and highlighted deep divisions over the Russian invasion of Ukraine.

The US president said he had met Chinese Premier Li Qiang at the G20 — a meeting the White House had not announced — and discussed "stability".

Semiconductor deal 

Global supply chain shocks and fears about US reliance on China for strategic resources have further driven the push to boost ties with the likes of Vietnam.

The new partnership includes an agreement on semiconductors, with the United States committing to help Vietnam develop its capabilities and expand production.

There is also a section on rare earth minerals, which used in the manufacture of high-tech devices such as smartphones and electric car batteries.