Kiev itself is not a dominant capital like Paris, said Bruce P. Jackson, president of the Project on Transitional Democracies, which has been working in Ukraine for 15 years.

“Kiev has always been more of a compromise than a capital, and if it loses the ability to compromise, it loses its credibility as a capital,” he said.

What worries him, Mr. Jackson said, is that the new government is too beholden to the people’s movement on the Maidan. He is also concerned that it is not reaching out sufficiently to the east and needs the credibility of both presidential and parliamentary elections to answer Mr. Yanukovych’s charge, echoed in Moscow, that those politicians of western Ukraine, who have regularly lost elections, have seized power instead.

In essence, he suggested, the revolutionaries “have knocked out the foundations of modern Ukraine,” and they need to be restored in a way that recognizes the diversity of the country.

Sudden, unmediated political change in countries like Ukraine rarely goes smoothly, he said, pointing to the Rose Revolution in Georgia, whose main proponents are now out of office and many in exile after an administration that inevitably produced some achievements but considerable disappointments, aided by Russian efforts to keep Georgia unstable.

Those efforts culminated in the 2008 Russian-Georgian war, when Russia provoked Georgia into skirmishes that prompted an invasion and the annexation of two Georgian regions with sizable numbers of ethnic Russians, Abkhazia and South Ossetia. That annexation has not been recognized internationally, but what is happening in Crimea seems drawn directly from the same playbook, but faster and with less pretense of responding to an endangered ethnic Russian population, which has been attacked by no one.

But Crimea is only the most vivid challenge to the credibility of the new Ukrainian government. Russia possesses numerous tools to destabilize the new powers in Ukraine, from financial instruments and customs duties to energy supplies and trade sanctions. A push for decentralization in Crimea can easily be followed by similar demands from eastern Ukraine, far more dependent on Russian trade. On Saturday, for example, thousands of demonstrators shouted pro-Russian slogans in Donetsk.