US Secretary of State Marco Rubio welcomed his counterparts from the so-called "Quad" to Washington in a shift of focus to Asia, after spending much of his first six months on the wars in Ukraine and the Middle East and on President Donald Trump's domestic priorities such as migration.

The four countries said in a joint statement that they were establishing the Quad Critical Minerals Initiative, aimed at "collaborating on securing and diversifying" supply chains.

They offered little detail but made clear the goal was to reduce reliance on China, which has used restrictions as leverage as the United States in turn curbs its access to semiconductors and as Trump threatens steep tariffs -- including on Quad countries.

"Reliance on any one country for processing and refining critical minerals and derivative goods production exposes our industries to economic coercion, price manipulation and supply chain disruptions," the statement said.

The ministers were careful not to mention China by name but voiced "serious concerns regarding dangerous and provocative actions" in the South China Sea and East China Sea that "threaten peace and stability in the region."

China holds major reserves of several key minerals including the vast majority of the world's graphite, which is crucial for electric vehicles.

In brief remarks alongside the other ministers, Rubio said he has "personally been very focused" on diversifying supply chains and wanted "real progress."

- US refocus on Asia -

The four-way partnership was first conceived by late Japanese prime minister Shinzo Abe, who saw an alliance of democracies surrounding China -- which has repeatedly alleged that the Quad is a way to contain it.

Rubio had welcomed the Quad foreign ministers on January 21 in his first meeting after Trump's inauguration, seen as a sign the new administration would prioritize engagement with like-minded countries to counter China.

But to the surprise of many, China has not topped the early agenda of Trump, who has spoken respectfully about his counterpart Xi Jinping and reached a truce with Beijing to avoid a wider trade war between the world's two largest economies.

Trump is expected to travel to India later this year for a Quad summit.

Both the Indian and Japanese foreign ministers said that they wanted the Quad to focus on a "free and open Indo-Pacific" -- a phrasing that is a veiled allusion to opposing Chinese dominance in Asia.

"It is essential that nations of the Indo-Pacific have the freedom of choice, so essential to make right decisions on development and security," Indian Foreign Minister Subrahmanyam Jaishankar said.

At Jaishankar's urging, the Quad condemned a May attack on the Indian side of Kashmir that killed mostly Hindu civilians and called for "the perpetrators, organizers and financiers of this reprehensible act to be brought to justice without any delay."

India in May launched air strikes in Pakistan, which it blamed for the attack. Pakistan denied responsibility and responded with its own attacks on the Indian military.

In a key concern for Japan, the Quad condemned North Korea for its "destabilizing launches" of missiles and insisted on its "complete denuclearization."

Trump, in one of the most startling moves of his first term, met with North Korea's reclusive leader Kim Jong Un, helping ease tensions but producing no lasting agreement.

Despite common ground on China, Quad members have differed on other hotspots, with the joint statement not mentioning Ukraine or Iran.

India has maintained its long relationship with Russia despite the invasion of Ukraine, while both India and Japan also have historically enjoyed cordial ties with Iran.