Asked whether Putin's decision to send in what he called “peacekeepers” amounts to an invasion, the European Union's foreign policy chief, Josep Borrell, said, “I wouldn't say that's a fully-fledged invasion, but Russian troops are on Ukrainian soil.” Use of the term “invasion” is important in this case because it sets the stage for what Biden said could become multiple waves of economic sanctions, in coordination with NATO allies and other countries who view Putin's aggression as a violation of international law and a threat to order in Europe. Sanctions are the West's main tool for pushing back because they have ruled out taking on Russia militarily.