When Russia invaded Crimea, it mobilized 150,000 troops along Ukraine’s eastern frontier. Most of those forces still menace Ukraine, with some 20,000 troops still occupying the peninsula while provocateurs sent by Moscow continue to stir unrest in the country’s eastern regions.
Brent Scowcroft Center Senior Fellow Ian Brzezinski writes in the Washington Post on how NATO can deter further Russian aggression:
NATO’s response to Russia’s invasion of Ukraine has drawn a red line, but it is one that leaves Ukraine militarily isolated, fending for itself. If the West’s economic and diplomatic sanctions are to deter Moscow from further military aggression, they must be complemented by a robust defensive strategy to reinforce Ukraine’s armed forces. NATO’s response has, by contrast, been underwhelming. The United States and Britain reinforced the air space of Estonia, Latvia and Lithuania with a handful of fighter jets, and AWACs patrols fly over Poland and Romania. The United States deployed about a dozen F-16s to Poland and sent an additional ship to the Black Sea. No ally appears to have mobilized any ground forces.