The United States and India will work together both in the bilateral and multilateral setups to support their shared vision of a free and open Indo-Pacific, the Biden administration's National Security Strategy said on Wednesday as it identified China as "one of the major threats" to American national security.

"As India is the world's largest democracy and a major defence partner, the US and India will work together, bilaterally and multilaterally, to support our shared vision of a free and open Indo-Pacific," said the Strategy, a declassified version of which was released.

The Strategy, which identified China as "one of the major threats to American national security," reaffirmed US' iron-clad commitments to its Indo-Pacific treaty allies - Australia, Japan, South Korea, the Philippines and Thailand.

"We will continue to modernise these alliances. We reaffirm our unwavering commitment to the defence of Japan under our mutual security treaty, which covers the Senkaku Islands," it said.

The US, India and several other world powers have been talking about the need to ensure a free, open and thriving Indo-Pacific in the backdrop of China's rising military manoeuvring in the region.

China claims nearly all of the disputed South China Sea, though Taiwan, the Philippines, Brunei, Malaysia and Vietnam all claim parts of it. Beijing has built artificial islands and military installations in the South China Sea.

"We have entered a consequential new period of American foreign policy that will demand more of the US in the Indo-Pacific than has been asked of us since the Second World War," according to the National Security Strategy document.

No region will be of more significance to the world and to everyday Americans than the Indo-Pacific, it said. "We are ambitious because we know that we and our allies and partners hold a common vision for its future."

The White House said the National Security Strategy outlines how the United States will advance its vital interests and pursue a free, open, prosperous and secure world.

"We will leverage all elements of our national power to outcompete our strategic competitors; tackle shared challenges; and shape the rules of the road," it said.

On China, it said the US will effectively compete with Beijing, which is the only competitor with both the intent and, increasingly, the capability to reshape the international order, while constraining a "dangerous" Russia.

"Strategic competition is global, but we will avoid the temptation to view the world solely through a competitive lens, and engage countries on their own terms," it said.

The White House said the US places a premium on growing the connective tissue on technology, trade and security between its democratic allies and partners in the Indo-Pacific and Europe because they recognise that they are mutually reinforcing and the fates of the two regions are intertwined.

"As we deepen our partnerships around the world, we will look for more democracy, not less, to shape the future. We recognise that while autocracy is at its core brittle, democracy's inherent capacity to transparently course-correct enables resilience and progress," said the White House about the national security strategy.

"As an Indo-Pacific power, the US has a vital interest in realising a region that is open, interconnected, prosperous, secure and resilient. We are ambitious because we know that we and our allies and partners hold a common vision for the region's future," it said.