President Joe Biden and Russian President Vladimir Putin are scheduled to speak via video call Tuesday amid mounting tension over the military buildup at the Russia-Ukraine border. The U.S. and other Ukrainian allies have warned Russia could soon launch an offensive, with U.S. intelligence warning last week the Kremlin could deploy as many as 175,000 troops early next year. Russia has rejected claims of an invasion and accused NATO and others of escalating the situation. Moscow has warned of consequences if Ukraine joins NATO.