KIEV - Ukraine's beleaguered President Petro Poroshenko announced on Wednesday that he and Russia's Vladimir Putin had agreed to a "permanent ceasefire" in the east of the former Soviet country.
Poroshenko's office said the agreement was reached in a telephone exchange that was preceded only a few hours by US President Barack Obama's arrival in former Soviet Estonia - a new NATO member seeking Western protection from an increasingly belligerent Kremlin.
Leaders from the 28-nation Western military bloc are due to agree on Thursday in Wales the creation of a 4,000-string force that could be deployed within two days to meet any perceived Russian military movements in eastern Europe.
Poroshenko's stunning announcement came more than four months into a war that has claimed more than 2,600 lives and plunged relations between Moscow and Kiev's Western allies to its lowest since the Cold War.
Putin and Poroshenko held a telephone exchange "that resulted in an agreement for a permanent ceasefire in Donbass (eastern Ukraine)," the Ukrainian president's office said in a statement.
"An understanding was reached concerning steps that will help to establish peace," the brief statement said.
Yet it was not immediately clear if rebel commanders - a loose band of mostly Russian-speakers who have no single leader and who have been making sweeping advances in recent days - were ready to either comply or disband.
The declared end to hostilities appeared to confirm Western allegations that Putin had a direct hand in the conflict even though he has denied any role and claimed he was in no position to negotiate on the rebels' behalf.
Russia however openly backs their drive for some form of independence from the pro-Western leaders who rose to power in Kiev after the February ouster of a Moscow-backed administration.
The Kremlin on Wednesday said only that Putin and Poroshenko had "exchanged opinions" about the crisis and gave no indication that a breakthrough had been reached.
"The views of the presidents of the two countries about possible ways out of this difficult crisis overlap to a considerable degree," Kremlin spokesman Dmitry Peskov told Russian news agencies.
Unbending NATO support
Obama arrived on Wednesday in Estonia to deliver an emblematic message of unbending NATO support for new members from ex-Soviet nations rattled by Russia's perceived actions in Ukraine.
The hostile barbs being traded by Moscow and the West in advance of Obama's visit to Europe hardly heralded the promise of a potentially major agreement being reached on Ukraine.
Obama's jumbo jet landed in the tiny Baltic nation - ruled for decades by Moscow and still completely reliant on Russian gas - a day after the Kremlin declared NATO a "threat" over its plans to boost defences in eastern Europe.
The Western military alliance has published satellite images purporting to show more than 1,000 Russian troops and heavy equipment moving into Ukraine's eastern districts to help separatist fighters push back government forces and establish a ground link with Crimea - a Black Sea peninsula Russia seized from Ukraine in March.
"NATO has played a leading role and produced ample evidence to indicate that Russia has intervened in ways that grossly violate the territorial integrity of the independent nation of Ukraine," said White House spokesman Josh Earnest.