If the past two weeks of war in Eastern Europe have shown us anything, it's that lots of Washington-based foreign-policy analysts and journalists love the idea of America imposing a no-fly zone over Ukraine. The first calls for declaring one came just a few days after Russia invaded the country. Most recently 27 foreign policy experts published an open letter in Politico making the case for what sounds like a more restrained ("limited") NFZ.
Limited or not, a NFZ over Ukraine would almost certainly mean war between the United States and Russia — an eventuality that just about everyone in our politics quite sensibly wants to avoid. That means imposing one is a terrible idea that people who should know better really ought to stop advocating.
No matter now limited, a NFZ requires a willingness to shoot down Russian planes that violate it — and a willingness to take the risk of our planes being shot down in the act of enforcement, both by Russian fighter jets and by ground-based anti-aircraft batteries. Even if both sides worked hard to call this air-to-air and surface-to-air combat something other than "war," an escalatory spiral would be highly likely to deliver us quite quickly to something that couldn't be described in any other way.
In a recent sharp essay, "The Ugly Truth About No-Fly Zones," author Damir Marusic discusses all of this. But he then goes further, to think through how a limited land war could emerge out of hostilities surrounding the enforcement of a NFZ — and how Russia could well prevail (or fight to a draw) in such a battle with NATO forces.
How so? By using tactical (smaller yield) nuclear weapons against our troops on the ground. The U.S. apparently has only 230 tactical nukes, while Russia has something on the order of 2,000 of them. Even assuming such a nightmarish scenario could be kept from escalating to the use of strategic nuclear weapons (including intercontinental ballistic missiles that can wipe out entire cities), it would be extremely bad, potentially leaving NATO forces outmatched and turning Ukraine (in Marusic's words) "into a radioactive wasteland."
Now, maybe NATO could still defeat a nuclear-armed Russian army using the "smart" conventional munitions the U.S. military has prioritized over tactical nukes. But that doesn't mean we should want to test the proposition.
America has vowed to defend NATO countries in the event of a Russian attack, but we have made no such promise to Ukraine. With hostilities already underway, we need to honor that commitment to restraint. It's supremely foolish to entertain doing otherwise.