USEC Inc., the U.S. executive agent for the Megatons-to-Megawatts program and the predecessor of Centrus Energy.
It was the U.S. entity that handled buying nuclear fuel derived from dismantled Russian warheads and turning that into ongoing commercial supply.
USEC bought down-blended uranium from Russia's Tenex, then moved to transitional commercial low-enriched-uranium contracts after 2013 — cementing U.S. dependency on Russian fuel — before becoming Centrus Energy.
It's the mechanism that tied American nuclear fuel procurement to Russia. The engine holds several readings open — a deliberate executive-agent role, a structural privatized-procurement setup, or just an ordinary fuel broker — treating all three as load-bearing.