The ongoing conflict in Ukraine has strained relations between the United States and Russia to their lowest point since the Cold War. With this dangerous downturn in ties has come a new challenge to the already tenuous nuclear cooperation between the two nations with the world’s largest weapons of mass destruction stockpiles. The New Strategic Arms Reduction Treaty (New START) is the last remaining bilateral agreement restricting the nuclear arsenals of Washington and Moscow. – Newsweek Photo: Russian Ministry of Defence