(Bloomberg) -- The US Department of Energy is asking Congress for funding to create a domestic source of enriched uranium, calling the country’s reliance on Russian imports a “vulnerability” for both national and economic security.

The letter from Energy Secretary Jennifer Granholm comes as the Biden administration continues to weigh slapping sanctions on Russia’s state-owned atomic energy company, Rosatom Corp., in response to the Kremlin’s invasion of Ukraine. 

Rosatom is the world’s biggest supplier of nuclear fuel and reactors, while Russia overall supplies more than 50% of global enriched uranium. Meanwhile, US enrichment capacity has waned after being undercut by state-subsidized competition, Granholm said in the letter, which was sent Friday to Senator Joe Manchin, the powerful moderate Democrat who chairs the Senate Energy and Natural Resources Committee. 

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“We should take steps to address this vulnerability and build a stronger domestic nuclear fuel supply for the future,” Granholm wrote in the letter, which asked for more investment to boost domestic manufacturing of low-enriched uranium as well as other forms of uranium needed for some advanced nuclear reactors.

Manchin of West Virginia, a key-swing vote who is playing a central role in Democrats’ efforts to pass Biden’s spending plan, has also endorsed increasing funding for domestic enrichment of the nuclear reactor fuel.

The US only has one remaining commercial enrichment facility, in New Mexico, which is owned by Urenco Ltd., a British, German and Dutch consortium. Bethesda, Maryland-based Centrus Energy Corp. is constructing an enrichment facility in Ohio.

“The Russian invasion of Ukraine and the corresponding impacts on global fuel supplies have cast into sharp relief the threat to global energy security from dependence on Russian-supplied fuels,” Granholm wrote. 

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