Ukraine’s forces are better armed, better trained, and more capable than they were in 2014, when “little green men” descended on Donbas and the Russian paratroopers took Crimea with little resistance. Also unlike in 2014, the territories Russia would be fighting over aren’t populated by Russian-speaking Ukrainians with as much affection for the Motherland as for the nation that issued their passports. The remnants of a routed Ukrainian military could mount a protracted campaign of resistance from such positions. Indeed, that may be Kyiv’s only hope. “One senior Ukrainian military official who spoke on condition of anonymity said that if all else failed, the military would simply open its weapons depots and allow the Ukrainian people to take whatever they need to defend themselves and their families,” the New York Times reported in December.

This is the nightmare scenario; and U.S. officials are fully aware of it. The Times reported this month that the Pentagon has warned Russia that an invasion of Ukraine would be followed by a “bloody insurgency similar to the one that drove the Soviet Union from Afghanistan.” That is as much a threat to Russia as it is to the Atlantic Alliance. Such a conflict on NATO’s borders would produce a destabilizing refugee crisis with millions of displaced Ukrainians all heading West. It would drive investment away from the Continent, exacerbating European political dysfunction and producing social malaise. It would likely necessitate the deployment of special forces into the semi-governed areas of Ukraine along NATO’s borders, increasing the risk of embroiling the West in a war it hoped to avoid and increasing the prospect of inadvertent conflict with Moscow.