WASHINGTON -- A Russian Su-27 fighter jet intercepted and struck the propeller of a U.S. military MQ-9 "Reaper" surveillance drone on Tuesday, causing it to crash into the Black Sea, in the first such incident since Russia's invasion of Ukraine over a year ago. NATO's Supreme Allied Commander Europe, U.S. Army General Christopher Cavoli, briefed NATO allies about the incident, which was roundly condemned by the White House and the Pentagon -- which warned of the risk of escalation. Two Russian Su-27 jets carried out what the U.S. military described as a reckless intercept of the American spy drone before...