I can imagine a “strong form” and a “weak form” version of each of these demands.

Putin’s four demands for a ceasefire with Ukraine:

• Ukraine to be neutral, no NATO membership
• Disarmament
• De-Nazification
• Zelensky agreeing negotiations on Donbas with Putin

Per Erdogan, Putin phone call, retold by senior Turkish official Kalin to BBC

— Ragıp Soylu (@ragipsoylu) March 18, 2022

The “weak form” version:

1. Ukraine rules out joining NATO (which it’s already done) but is free to join the EU.
2. Ukraine agrees not to field certain narrow categories of weapons but is free to enter into NATO-like security guarantees with the west.
3. Ukraine makes some sort of generic rhetorical gesture denouncing Nazism. “Perhaps it will be enough for Ukraine to condemn all forms of neo-Nazism and promise to clamp down on them,” the BBC said yesterday in reporting on Putin’s call with Erdogan.
4. Ukraine concedes Crimea to Russia but Russia agrees to let Ukrainians in the east decide their own fate via a UN-supervised referendum. Which, given how this war has gone, might well end in the Donbas reverting to Ukraine.

The “strong form” version:

1. No NATO membership for Ukraine — and no EU membership either. Neutrality means neutrality, not a state formally aligned with the west.
2. The class of weapons prohibited to Ukraine is large and any western security guarantees for Ukraine are weak, with enough legal wiggle room for the west to decline to intervene the next time Russia tries this.
3. “Denazification” means that Ukraine must disarm far-right militias like the Azov Battalion, risking civil war.
4. Ukraine concedes Crimea and the Donbas to Russia, and maybe the corridor between them in the south that Russia conquered during the war.

One way to understand the war going forward is as a test of strength to see whether the weak form or the strong form of Putin’s demands prevail. The better Ukraine does, the weaker Putin’s interpretation of his demands will get. They’ve done well enough already that Putin’s initial vision of toppling Zelensky’s government and replacing him with a puppet ruler now seems to be off the table. At this stage, even if Russia could pull it off, what would be the point? Moscow must realize by now that that government wouldn’t last long.

The two sides have already reached an impasse on one condition, the most important of the four:

Zelensky advisor Oleksiy Arestovych says Ukraine will not budge on recognising 1991 borders

So no compromises on Crimea, Donetsk or Luhansk are on the cards

— Samuel Ramani (@SamRamani2) March 17, 2022

I think Ukraine might relinquish Crimea if that became the last stumbling block to a deal. But conceding a disputed territory like the Donbas would feel perverse twice over, rewarding Russia for its aggression in invading Ukraine and rewarding its army for having performed incompetently in the field. There’ll have to be a compromise on the Donbas, assuming Putin’s ego will permit one.

In the meantime, he has every incentive to keep pounding Ukrainians in hopes of moving Zelensky off the weak form of Russia’s demands and towards the strong form:

UK Chief of Defence Intelligence: “Russian operations have changed. Russia is now pursuing a Strategy of Attrition. This will involve the reckless and indiscriminate use of firepower. This will result in increased civilian casualties [&] destruction of Ukrainian infrastructure"

— Shashank Joshi (@shashj) March 18, 2022

⚡️ Over 1,300 civilians still stuck under Mariupol's destroyed theater.

According to Ombudsman Lyudmila Denisova, 130 people were rescued from the Mariupol theater destroyed by a Russian strike on March 16.

The vast majority of people remain stuck under the rubble.

— The Kyiv Independent (@KyivIndependent) March 18, 2022

And of course the Ukrainians have every incentive to keep pounding his army to get Putin to do the opposite:

A former British army special forces officer passing through Kyiv this week offered his analysis: “They’re not looking after their dead, and an army that does that tends to lose.” Morale of the Russian soldiers is low, poor, rotten — pick an adjective. The proof of that is the litter of corpses in Russian uniform after any major battle…

In war, quantity is quality. The Russians hit Ukraine with 200,000 troops. But the Ukrainians have 200,000 in their armed forces and a further 100,000 in the police and other trained militia, even before you start counting the tractor drivers among the many willing volunteers. Invaders need a 3:1 ratio to defenders, so the Russians needed close to 1 million troops to have a good chance of winning. Which is why they are losing.

The Ukrainians say that 13,700 Russians have died. These numbers are impossible to verify, but pictures of the dead and the battles the Russians have lost suggest this number is not absurd. Out of caution, let’s assume the number of Russian dead to be 10,000. There is a rule of thumb that for every corpse, there are three injured soldiers. That would point to 30,000 injured or running away, so it’s likely that the Russians have lost 40,000 of their fighting force in the first three weeks of the war. That’s a fifth of the force they started with: not good for the collective spirit.

That’s the point of Ukraine’s new counteroffensive. It’s not to recapture land from the Russians and to hold it, risking a direct confrontation. Ukraine’s strategy calls for spreading out its forces, staying nimble, and making lightning strikes on Russian supply lines to bleed the army of men and fuel. The goal of the counteroffensive is simply to convince the Russians that they can’t win. The more casualties they suffer, the more their battalion groups will become ineffective, the less ability they’ll will have to advance. Ideally the army would end up trapped behind enemy lines and unable to move much in any direction or to be quickly resupplied. That’s the scenario in which the “weak form” of Putin’s demands is the only one left on the table.

The scenario in which the “strong form” is the only one left is too ugly to think about, so let’s not.