There are 74,000 U.S. military personnel in Europe, including the United Kingdom, Italy, France, and Spain, with the largest number (36,000) in Germany. Not all these people are front-line fighters. Many are involved in logistics, maintenance, and other tasks. There is a broader, 40,000-strong NATO response force, too, and some thousands of these troops are in the front-line Baltic nations of Latvia, Estonia, and Lithuania. All told, fewer than 100,000 NATO forces in Europe are even close to being ready to fight.

The Russian force brought together for the Ukraine invasion is double that, about 190,000, and total Russian forces number 900,000.

Could NATO bring a larger force to bear? You bet. But it would take months, according to Shlapak.

For NATO to truly be ready to face down Russia, at least 100,000 more troops would have to be transported to Europe from the United States, Mark Cancian, of the Center for Strategic and International Studies, told The Week. Weapons, equipment, and logistics would all have to be scaled up accordingly.