The US and Russia have concluded a third round of arms-control talks and are still at odds over several key issues. However, the two sides showed willingness to possibly extend the New Strategic Arms Reduction (START) Treaty before it expires in 2021. New START, which caps the number of deployed long-range nuclear warheads each country can have, expires in February 2021, unless the two sides agree to extend it for five years. It is their last remaining bilateral nuclear-arms-control agreement. The US has urged China to join the negotiations — a proposal rejected by Beijing. Moscow believes that if China is to join, then Britain and France should also be engaged in an even wider process.