What If the War in Ukraine Spins Out of Control?

The war in Ukraine will soon enter its sixth month. For all the talk of Russia crossing the West’s redlines with its conduct in the war and of the West crossing Russia’s redlines with its military assistance to Ukraine, the true redlines have not yet been breached. At the outset of the war, both sides hashed out a set of invisible rules—unspoken but nonetheless real. They include Russia’s acceptance of allied heavy-weapons deliveries and intelligence support for Ukraine, but not the use of Western troops. And they include Western states’ grudging acceptance of Russian conventional warfare