From the outset of Russia's war on Ukraine, the crucial question hasn't changed: Can Vladimir Putin be defeated at an acceptable cost? Despite all we now know about Russia's military incompetence and the courage and skill of Ukraine's forces, the answer is still uncertain.
This leads to an uncomfortable conclusion, one that President Joe Biden showed no trace of understanding in his speech at the United Nations last week.
Planning for the end of this conflict needs to weigh outcomes that are disappointing, even disgraceful, for the sake of avoiding those that are catastrophic.
The idea of an off-ramp for Putin strikes many as repugnant — and now, for good measure, entirely unnecessary. Ukraine is winning! Why help Russia snatch so much as a partial victory from the jaws of defeat?
The "Ukraine must win" chorus never clearly sets out what Russia's defeat really involves. Perhaps it means that Russia is pushed back behind its pre-2014 borders and then just comes to terms with it. Or maybe Putin's humiliation causes domestic opposition to explode and he's removed; his successor is someone the West can do business with; Russia's claims to superpower status collapse; and its demotion to second-tier status is acknowledged and accepted.
All good stuff, to be sure, and nothing is impossible. But, to put it mildly, these futures aren't assured.
As governments gathered for the U.N. meeting, Putin announced his intention to prolong the war with a "partial mobilization" that in due course will field another 300,000 soldiers. And he underlined his threat to use nuclear weapons: "Russia will use all the instruments at its disposal to counter a threat against its territorial integrity. This is not a bluff."
Soon that notion of territorial integrity might include areas Russia currently occupies and intends to annex.