"His use of the phrase ‘nuclear tests’ suggests actual nuclear detonations, whereas the call for tests ‘on an equal basis’ to Russia and China would be tests of nuclear weapons delivery systems. This is a major difference, and clarification by the administration is urgently needed," she said.

Russia has in recent months attacked Ukraine with a cruise missile whose secret development prompted Donald Trump to abandon a nuclear arms control pact with Moscow in his first term as U.S. president...

Russia has deployed around 170,000 troops in Ukraine’s eastern Donetsk region where they are trying to capture the stronghold of Pokrovsk in a major push for a battlefield victory, Ukrainian President...