The untested pro-Western interim team in Kiev is grappling with the dual threats of separatism and default as it tries to recover from three months of protests that triggered pro-Russian president Viktor Yanukovych's ouster following a week of carnage in which nearly 100 people died.
The wave of secessionist sentiment that gripped the Russified southeastern parts of Ukraine following the fall of the pro-Kremlin regime boiled over in Crimea as an angry crowd of a few thousand led by pro-Russian Cossacks squared off against a force of a similar size spearheaded by Muslim Tatars.
Tensions were ratched up still further when Putin ordered the military to undergo snap readiness drills -- one of several announced in recent months -- across a western swathe of Russia that borders the northeast corner of Ukraine.
"The commander-in-chief has set the task of checking the capability of the armed forces to deal with crisis situations posing a threat to the military security of the country," Defence Minister Sergei Shoigu said.
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Russia has been venting daily outrage at the meteoric turn of events in a neighbour that Putin views as vital to his dream of building a post-Soviet alliance that could rival the EU and NATO blocs.
Both US Secretary of State John Kerry and British Foreign Secretary William Hague gave the new leaders crucial backing on Tuesday and rejected Moscow's claim that Ukraine was being forced to make a choice between East and West.