air defense missiles, multiple officials tell cnn. the biden administration is weighing the consequences of such moves. with some administration officials concerned they could be seen by the kremlin as a major escalation. anti-tank missiles are effective against the t-80 tanks, which the russians are employing in these efforts against ukraine right now. reporter: the u.s. has been warning allies of a possible russian invasion. with just a short window to prevent russia from taking action, top u.s. officials increasingly sound the alarm publicly. we have real concerns about russia s unusual military activity on the border with ukraine. we re not sure exactly what mr. putin is up to. reporter: a top ukrainian intelligence official claims in an interview with the military times that russia has more than 92,000 troops amassed near ukraine s border that are preparing to attack in january or february. these satellite images from
additional weapons to ukraine to help fortify the country from a potential russian invasion. this as moscow is ramping up its presence at the border. we have cnn anchor and correspondent jim sciutto with us on this story. this would be, to be clear, american assets on the ground. no question. as russia built up this force here, i m told the u.s. has a two-prong strategy. internationalize the crisis, get allies on board, warn russia with one voice, and the other thing, not give russia an expectation this would be a swift and easy invasion. two elements here. one, send more weapons to the ukrainians. also, the possibility of u.s. trainers and advisers. reporter: with concerns growing ability a russian military build-up on the ukrainian border, the biden administration is considering sending military trainers to the region. and military element that could include javelin anti-tank missiles and momortars, as wells