KIEV, Ukraine
— Ukraine’s failure to enforce its own ultimatums and its appeal on Monday to the United Nations to send peacekeepers laid bare a grim reality for the shaky government in Kiev, where political leaders and security forces have few reliable ways to confront Russian-backed separatists in the restive east. A deadline set by Ukraine’s acting president for the start of a “large-scale antiterrorist operation” in the east passed without any clear police or military intervention. Meanwhile, pro-Russian militants seized yet another government building in the Donetsk region, bringing to at least nine the number of eastern towns now swept up in an insurgency. The country’s acting president, Oleksandr V. Turchynov, asked the United Nations to send peacekeepers. But the move was widely viewed as an act of desperation, given that Russia holds a veto at the United Nations Security Council and is unlikely to assent to a such a request. The confused and passive response underscored Kiev’s limited options in challenging pro-Russian militants and their backers in Moscow.

Too assertive a response could cause heavy civilian casualties and play into Moscow’s narrative that Russians and Russian speakers in Ukraine are threatened and need protection. Too timid a response risks inviting more meddling from Moscow or giving free rein to local armed militants.  Ukraine’s armed forces, demoralized and underequipped, are so short of funds that when the government ordered them on high alert last month as Russian forces seized Crimea, a Ukrainian billionaire had to buy the military fuel. The businessman, Ihor Kolomoysky, now the governor of the Dnipropetrovsk region next to Donetsk, said he put up around $5 million of his own money to pay for gasoline and batteries so that Ukrainian military vehicles could leave their garages and helicopters could get off the ground. Ukraine’s intelligence agency, the State Security Service, known as the SBU, is so riddled with Russian informers that when John O. Brennan, the C.I.A. director, visited Kiev over the weekend on a supposedly secret trip, Russian state news media swiftly revealed his visit and declared it evidence that Washington was calling the shots in Ukraine and pushing for a crackdown in the east. More