Washington: The US administration is increasingly alarmed over the possibility that Russia is supporting China's build-up of nuclear weapons by supplying it with highly enriched uranium, Nikkei Asia reported. During a congressional hearing on Wednesday, US Secretary of State Antony Blinken said that China's political and to some extent material support for Russia goes against the interests of the US in bringing an end to the war.

"Their diplomatic support, their political support and to some extent material support for Russia certainly goes against our interests in bringing this war to an end," Nikkei Asia quoted Antony Blinken as saying. Blinken said that China is not providing deadly weapons to Russia. However, he underscored that the two nations are partners. He said, "They talked about a partnership with no limits."

Further, as per the news report, the new area of concern expressed by the Biden administration stems from the nuclear cooperation between Russia and China. At a hearing in March, John Plumb, the assistant secretary of defence who oversees space and nuclear policy, called it "very troubling" to see Russia and China cooperating on this, the report stated further.

Plumb said, "They may have talking points around it, but there's no getting around the fact that breeder reactors are plutonium, and plutonium is for weapons."

He spoke about the risk that Russia's provision of enriched uranium could result in China expanding its nuclear arsenal.

Speaking to Nikkei Asia, a senior State Department official said, "Responsible nuclear states should not be feeding into [China's] nuclear programs with fissile material without understanding the escalatory potential, without understanding the destabilizing nature, without understanding the consequences of that transfer."

The US official said Washington has made little to no progress in establishing a dialogue with China over nuclear capabilities and urged Beijing to offer greater transparency on its nuclear programs, as per the news report.

In US Congress, House Select Intelligence Committee Chairman Representative Mike Turner and two other senior Republicans sent a letter to the White House National Security Advisor Jake Sullivan. They warned him that Russia and China's "nuclear cooperation goes much farther than just civilian projects."

The US representatives in the letter recommended that the Biden administration should make use of all tools at its disposal to stop Russia's state-owned nuclear company Rosatom and China's "dangerous cooperation", as per the Nikkei Asia report.

The US administration has found that China is expanding its nuclear capabilities. In an annual report released in November last year, the US Department of Defence estimated that China will triple its stockpile to 1,500 nuclear warheads by 2035.

Jacob Stokes, a senior fellow at the Washington-based Center for a New American Security think tank said that the constraint on China's arsenal has been a lack of fissile material to create new weapons, as per the news report.

Stokes further said, "Russian shipments provide China with uranium that, with additional processing, could go into new nuclear warheads, thereby alleviating that constraint."

Recently, Chinese President Xi Jinping visited Moscow and held a meeting with their Russian counterpart Vladimir Putin. The two leaders issued a joint statement on deepening their comprehensive partnership and strategic cooperation.

Vladimir Putin and Xi Jinping also released a joint statement on plans for economic cooperation between the two nations until 2030.