Ukraine's embattled interim leaders have been waging an uphill battle to keep their culturally splintered nation of 46 million together after last month's ouster of a pro-Kremlin regime and subsequent loss of Crimea to Russia.
An eery echo of the Black Sea peninsula's crisis sounded on Sunday when militants stormed a series of strategic government buildings across a swathe of heavily Russified eastern regions and demanded that Moscow send its troops for support.
An urgent deployment of security forces saw Kiev also regain control of an administration building in Kharkiv and the security service headquarters of Donetsk.
But the separatists still held on to the security service building in the city of Lugansk after breaking into its massive weapons cache and releasing several activists who had been accused of plotting to stage a coup.
And hundreds of militants remained holed inside the Donetsk administration building a day after proclaiming the creation of an independent "people's republic" and demanding that an independence referendum be held before May 11.
But calm had returned to the city of Kharkiv after a night of violence that saw retreating militants throw Molotov cocktails at the administration building as hundreds of police regained control of it.
The months-long crisis threatens not only to splinter the vast nation on the EU's eastern frontier along its ethnic divisions but also plunge Moscow's relations with the West to a low that may take decades to repair.
"It would have grave consequences for our relationship with Russia and it would further isolate Russia internationally," said the Western military alliance leader.