After decades of collaboration, Washington, D.C., and Moscow in December ended their joint efforts to improve the security of Russia’s nuclear stockpile. Though nuclear security projects between the former Cold War antagonists have been winding down for some time, the events of the past year in Ukraine are seen to have brought to an abrupt close the much-heralded Nunn-Lugar Cooperative Threat Reduction program.

The end, according to a recent Boston Globe report, occurred at a meeting in a Moscow hotel during which Russian officials informed their U.S. counterparts that the Russian state atomic energy firm Rosatom would no longer accept U.S. Energy Department assistance in upgrading physical security at a number of sites in the country housing sensitive nuclear material. That work was the last active remnant of Nunn-Lugar activities in Russia following the Kremlin’s 2013 decision to cease Russian Defense Ministry involvement in the program while allowing some cooperative activities between the Energy Department and Rosatom to continue.