Putin is demanding that a large tract of eastern Ukraine, taken by force by his separatist proxies in recent weeks, be granted internationally licensed autonomy and that a new frontline be recognised as a basis for a putative ceasefire.
The parallel might be 1991 in Croatia when the Serbs took a quarter of the country and then consolidated their grip behind lines patrolled by UN peacekeepers. It crippled and destabilised Croatia.
European policymakers say this is Putin’s aim in Ukraine. In Croatia the land-grab lasted four years until Zagreb, gradually armed by the Americans and Europeans, quickly routed the Serbs militarily.
The big difference then was that the Serbs were stretched by a bigger war next door in Bosnia where eventually Nato bombed them to the negotiating table. That will not happen with the Russians.
Arming the Ukrainians, meanwhile, will open up big divisions between the Americans and most Europeans. Putin is playing on those divisions as he plays on splits between the Europeans. He does not need to try very hard. The divisions are ever-present over sanctions.
On Monday the EU will impose more sanctions, extending a blacklist of pro-Russia separatists and Russians by 19 names. These penalties are minor. The broader economic sanctions in force against Russian banks and companies are more serious. They lapse in July unless extended by all EU governments.
Last year the biggest opponent was Matteo Renzi, the Italian prime minister, whose then foreign minister, Federica Mogherini, now coordinates EU foreign policy. The new leftwing pro-Russia Greek government may be this summer’s problem.