Ukrainian officials see an intensification of Russian military aggression as “inevitable,” a senior U.S. diplomat said amid spars with Russian President Vladimir Putin’s envoy at the United Nations Security Council.

“We have worked with the Ukrainians, at their request, to provide assistance to them so that they can prepare for what they see as inevitable,” said U.S. Ambassador to the U.N. Linda Thomas-Greenfield on Monday at a Security Council meeting, referring to the influx of military assistance to Ukraine in recent weeks. “That is so that they can be prepared.”