According to a Reuters report, NATO said on Monday it was putting forces on standby and reinforcing eastern Europe with more ships and fighter jets, in what Russia denounced as Western hysteria in response to its build-up of troops on the Ukraine border. The U.S. Department of Defense in Washington said about 8,500 American troops were put on heightened alert and were awaiting orders to deploy to the region should Russia invade Ukraine. Tensions are high after Russia massed troops in reach of its neighbor's border, surrounding Ukraine with forces from the north, east, and south. Russia denies planning an invasion, and Moscow is citing the Western response as evidence that Russia is the target, not the instigator, of aggression. President Joe Biden, pushing for transatlantic unity, held an 80-minute secure video call with a number of European leaders on Monday from the White House Situation Room to discuss the Ukraine crisis. The call, which included the leaders of Germany, France, Italy, Britain, and Poland, showed "total unanimity," according to President Biden. So far, NATO has about 4,000 troops in multinational battalions in Estonia, Lithuania, Latvia, and Poland, backed by tanks, air defenses, and intelligence and surveillance units. U.S. officials said the Pentagon was finalizing efforts to identify specific units that it could deploy to NATO's eastern flank.