Ukraine’s backers have proposed two pathways to victory. The first leads through Ukraine. With help from the West, the argument runs, Ukraine can defeat Russia on the battlefield, either depleting its forces through attrition or shrewdly outmaneuvering it. The second path runs through Moscow. With some combination of battlefield gains and economic pressure, the West can convince Russian President Vladimir Putin to end the war—or convince someone in his circle to forcibly replace him.

But both theories of victory rest on shaky foundations. In Ukraine, the Russian army is likely strong enough to defend most of its gains. In Russia, the economy is autonomous enough and Putin’s grip tight enough that the president cannot be coerced into giving up those gains, either. The most likely outcome of the current strategy, then, is not a Ukrainian triumph but a long, bloody, and ultimately indecisive war. A drawn-out conflict would be costly not only in terms of the loss of human life and economic damage but also in terms of escalation—including the potential use of nuclear weapons.