MOSCOW — Under the attentive eye of Russian state television, several hundred pro-Russian demonstrators in the city of Donetsk, in eastern Ukraine, declared on Monday that they were forming an independent republic and urged President Vladimir V. Putin to send troops to the region as a peacekeeping force, even though there was no imminent threat to peace.
The actions in Donetsk and two other main cities in eastern Ukraine, which included demands for a referendum on seceding from Ukraine and joining Russia, seemed an effort by the activists to mimic some of the events that preceded Russia’s invasion and annexation of Crimea. However, there were no immediate indications that the Kremlin was receptive to the pleas.
While widely regarded as political theater supported if not directed by the Kremlin, the protests could help promote what analysts say is Russia’s primary goal of destabilizing the shaky government in Kiev, preventing it from drifting further into the West’s orbit and giving Moscow leverage over the country’s future ahead of presidential elections in May.
The turmoil in eastern Ukraine also makes it extremely difficult for the provisional government in Kiev to begin putting in place an array of austerity measures and financial overhauls required by the International Monetary Fund as a condition for an $18 billion loan package that the country desperately needs to avert a financial default.
The protesters themselves may be trying to provoke a violent response from Kiev, analysts say, hoping to provide the pretext for a Crimea-like military incursion in a country that Moscow considers an integral part of historical Russia.
The Ukrainian authorities seemed to be responding cautiously, but made several enforcement efforts throughout Monday night. In Kharkiv, they expelled demonstrators from the regional administration building, which was then briefly set ablaze as protesters threw firebombs. The first was extinguished, but at least two people were injured in clashes with the police outside the building, local news agencies reported.
In Donetsk, the authorities were able to retake control of the headquarters of the security services, but remained in a standoff with demonstrators occupying the regional administration building. Several thousand people remained on the streets early Tuesday morning, and tension remained high across the region, with a continuing risk of violence.
In recognition of the potential dangers, Secretary of State John Kerry told the Russian foreign minister, Sergey V. Lavrov, in a phone call on Monday that there would be “further costs” if Russia took additional steps to destabilize Ukraine, the State Department said.
Mr. Kerry said in the call that the United States was monitoring with growing concern the pro-Russia protests in Donetsk, Kharkiv, Luhansk and Mariupol, and did not believe they were a “spontaneous set of events,” said Jen Psaki, the State Department spokeswoman.
“He noted in particular the recent arrests of Russian intelligence operatives working in Ukraine,” Ms. Psaki added.
The Obama administration has warned Russia that it is prepared to impose additional sanctions if Russia intervenes militarily or covertly to undermine the new Ukrainian government, a point Kerry repeated on Monday.