Russia is providing reactor fuel to China, helping the country fuel its nuclear capabilities, according to U.S. defense officials.
Officials say Russia is aiding China's capacity for nuclear-capable intercontinental ballistic missiles (ICBMs), reported Newsweek.
The agreement between the two nations will allow China to speed up its nuclear arsenal. The Pentagon said China could double its stockpile of nuclear warheads by 2030.
"China's silo expansion is being fueled by Russia — literally — as Moscow supplies China with highly enriched uranium reactor fuel, which supports the production of weapons-grade plutonium," said Vipin Narang, the acting assistant secretary of defense of space policy.
Narang made the remarks at an event hosted by the Center for Strategic and International Studies.
"We assess that the PRC (People's Republic of China) has likely completed silo construction and has begun loading them with missiles," Narang said.
The move, Narang said, allows China to enhance the speed at which it could undertake a nuclear counterattack. The new abilities, aided by Russia, were not anticipated over a decade ago when the United States created its nuclear modernization program, Narang said.
The evolution is "likely to become a defining feature of this new nuclear age," he said.
"If our adversaries continue down their current paths, the United States — alongside our allies and partners — is ready, willing, and able to confront the challenges of a new nuclear age," Narang said.
U.S. officials have long expressed concerns over China's establishment of a nuclear arsenal. A bipartisan commission said it's imperative for the United States to keep pace with adversaries and continue modernizing the country's nuclear capabilities.
Secretary of Defense Lloyd Austin and Antony Blinken co-wrote a statement warning of China's nuclear expansion and stressing the importance of the United States creating a "nuclear umbrella."