Some 16 hours of talks in the Belarussian capital Minsk — which saw one reporter collapse with high blood pressure — produced an agreement on a ceasefire to take effect from Sunday and the withdrawal of troops.

The deal — overseen by President Vladimir Putin and Ukrainian leader Petro Poroshenko — staves off an immediate threat of Washington beginning to supply weapons to Kiev but is no guarantee that fighting will not resume in the future, analysts said.

The agreement signed by Kiev and rebels left many of the trickiest issues unresolved: the depth of decentralisation, control of the Ukraine-Russia border and the size of the separatist regions to be given autonomy.

“It is unclear how a long-term solution will come out of today’s agreements,” Nikolai Petrov, a professor at the Moscow-based School of Higher Economics, told AFP.

“It is impossible to expect a serious long-term solution to this problem until it becomes clear how the political situation will develop in Kiev and what ties there will be between Russia and the West.”

Petrov compared the deal, agreed with the support of German Chancellor Angela Merkel and French President Francois Hollande in Minsk, to an earlier truce accord that was agreed there in September which was widely flouted.

-Fighting likely to resume-

The deal at least “reduces the probability of the US and other Western countries supplying Ukraine with defensive weapons,” said chief economist Holger Schmieding of German bank Berenberg.

Observers have warned that if the United States gets involved militarily, a regional conflict that has already claimed more than 5,300 lives could enter a dangerous new stage and become a proxy war between Russia and the West.

Even if Moscow and the Ukraine rebels move to honour the new agreement, the deal still allows them to overrun the strategic railway hub of Debaltseve, Schmieding said.

“Russia has the edge on the ground,” he wrote in a note to clients.

Speaking to reporters after the talks, Putin — who managed to leave without signing anything — indicated that fighting near Debaltseve was a key sticking point in the negotiations.

The rebels have encircled up to 8,000 Ukrainians troops and expect them to lay down arms, he said.

The Ukrainian army flatly denied the claim, saying fighting in the area was continuing.

Security analyst Pavel Felgenhauer said both sides could use a breathing space and in any case the fighting on the ground will become difficult during a spring thaw.

“It was impossible for rebels to advance further without Russia sharply ramping up its intervention and the use of aviation,” he told AFP.

“It’s not a good time to fight right now. It’s beginning to thaw,” said the columnist for the opposition Novaya Gazeta newspaper in Moscow.

“Things will grind to a halt until the summer or later spring when the ground dries out — then hostilities will resume and intensify.”

-‘Fragile equilibrium’-

Analysts said that upcoming political and economic events both in Russia and Ukraine will serve as a bellwether indicating the conflict’s future direction.

“It’s a very fragile equilibrium,” said Petrov. “It depends what happens first — a large-scale political and economic crisis in Ukraine or whether Russia will weaken under Western sanctions and will face problems at home.”

Washington and Brussels have slapped several rounds of tough sanctions against Russia. The European Union said new sanctions would depend on Russia’s willingness to rein in the separatists in Ukraine.

Yevgeny Minchenko, director of the International Institute of Political Analysis, a Moscow think tank, said there was no quick settlement in sight for a crisis that may well become Europe’s own “Arab-Israeli conflict.”

“Russia’s aim has been repeatedly stated – for Ukraine to become a friendly state and to prevent any ‘export’ of instability from that country to Russia,” the Kremlin-friendly analyst told AFP.

In Kiev, Volodymyr Gorbach, an analyst with the Institute for Euro-Atlantic Cooperation, said Russia and the separatists simply had no interest in a lasting settlement.

“They will use the latest agreements to win a respite and prevent new Western sanctions,” he told AFP.

The main result of the Minsk summit, he said, was “the establishment of a genuine anti-Putin coalition: Poroshenko-Hollande-Merkel.”