Stakes mounting as Putin, Biden to hold summit

Ukraine’s president said Monday that his country’s military is ready to “derail” any invasion by Russian forces — a stark warning ahead of President Biden’s high-stakes virtual summit with Russian President Vladimir Putin on Tuesday morning amid soaring tensions and military buildups on both sides of the old Cold War divide in Europe.

U.S. intelligence sources say Moscow has massed some 70,000 troops near its neighbor and could be ready to invade as soon as next month. Russian officials said the U.S. and NATO have been provocative by rushing to arm Ukraine and challenging Russian forces in...