Ukraine's warring sides agreed Friday to stop shooting and disengage their forces, a move that could lead to talks on a permanent political settlement after five months of civil war between Russian-backed rebels and pro-Kiev forces.
But the devil will be in the details, which have yet to be finalized between representatives of Kiev, Moscow, the Ukrainian rebels and the Organization for Security and Cooperation in Europe (OSCE), which are meeting in Minsk, Belarus. Early statements from the different sides suggest they remain very far apart, including on practical steps for a cease-fire after the two sides fought to a standstill in recent days.
Experts say they doubt the ceasefire will last long without strong pressures from Moscow on the rebels to halt their advance, and on Kiev from the West to accept some sort of autonomy for the two rebel held regions of Donetsk and Luhansk, known as the Donbass.
Via Twitter, Ukrainian President Petro Poroshenko described the deal as a "preliminary truce" that could lead to an exchange of prisoners. Prime Minister Aseniy Yatseniuk said that Kiev expected the deal would lead to a full withdrawal of Russian troops and a restoration of Ukrainian control of the border. The two leaders differ on which international body should monitor any cease-fire: Mr. Yatseniuk called for NATO monitors, while Mr. Poroshenko said the job could be done by the OSCE, which is more to Moscow's liking.
Speaking in Wales, NATO secretary-general Anders Fogh Rasmussen was cautiously optimistic. "One thing is to declare a ceasefire... the next and crucial step is to implement it in good faith," he told journalists. "But so far so good. I hope that this step could be the start of a constructive political process."
For Ukraine, at least a temporary cessation of hostilities has become an urgent necessity. Over the past 10 days Ukrainian forces have been routed on the battlefield by rebels – allegedly backed by Russian troops. The pro-Russian rebels have largely lifted the sieges on their capital cities, Donetsk and Luhansk. The separatists have also pushed towards the port city of Mariupol, potentially carving out a new land-sea corridor to Russia.
"Kiev has a dire need for a breathing space. Its forces are on their last legs, exhausted and losing ground," says Sergei Strokan, foreign affairs columnist for the Moscow daily Kommersant.
On Wednesday, President Vladimir Putin proposed a "road map" that included a ceasefire, a Ukrainian pullback to territory beyond artillery range of any rebel-held population center, a no-fly zone, international monitoring, humanitarian aid corridors and a full exchange of prisoners.
"Moscow has accomplished a key goal, in getting the rebel leaders to be accepted as participants in the talks," says Nikolai Svanidze, a leading Russian TV commentator. "Now Russia's hands are freed. Unfortunately, it is not guaranteed that the rebels will stop fighting just because Moscow tells them to."
Rebel leaders have backtracked on previous pledges to negotiate autonomous status with Ukraine and insisted on seeking full independence. Not is it clear that pro-Kiev militia fighting in the east with private financing would adhere to a deal, particularly if it freezes rebel control of Donbass. These and other fighters represent wild cards as they are only nominally answerable to Moscow or Kiev.
"Of course the rebels know their offensive cannot go on forever, and that if Moscow pulls support from them they will be in trouble. They need to stop and convert their battlefield gains into some kind of lasting political status. But it may not be easy convincing them that the time to do that is now. They're on the move, they're winning, so why would they stop?" asks Mr. Strokan.
By throwing its support behind the peace talks, Russia may be hoping to forestall a new round of US and European sanctions, which Western leaders have said could be put on hold if a cease-fire holds.
Five months of fighting in Ukraine have killed at least 2,600 people and displaced around a million.
"Any agreement is good in principle, but let's see how it works in reality," says Vladimir Zharikhin, deputy director of the Kremlin-funded Institute of the Commonwealth of Independent States in Moscow. He points out that it only takes one part to disrupt a cease-fire. "There is a certain amount of chaos down there, not all forces are under any kind of central control."