The last remaining nuclear arms pact between Russia and the United States is set to expire this week, removing any caps on the two largest atomic arsenals for the first time in more than a half-century. The end of the New START Treaty sets the stage for what many fear could be an unconstrained nuclear arms race. Russian President Vladimir Putin has declared his readiness to stick to the treaty's limits for one more year if Washington follows suit, but U.S. President Donald Trump has been noncommittal about extending it. Arms control advocates have warned that the treaty's termination would fuel a renewed arms race.

Russian President Vladimir Putin says Moscow has tested a new intermediate-range missile in a strike on Ukraine and that it could use the weapon against countries that have allowed Kyiv to use their missiles to strike Russia. Putin said during a nationwide TV address that the Russian strike Thursday on the central Ukrainian city of Dnipro came in response to Ukrainian strikes on Russian territory this week that used U.S. and British longer-range missiles. Two people were wounded in the attack. Putin declared that Russia would issue advance warnings if it launches more strikes with such missile against Ukraine to allow civilians to evacuate to safety. He warned that U.S. air defense systems wouldn't be capable of intercepting Russian missiles.