Mr. Putin’s decisions since the crisis began reflect instincts, political skills and emotions that have characterized his 14 years as Russia’s paramount leader, including a penchant for secrecy, loyalty and respect, for him and for Russia. They also suggest a deepening frustration with other world leaders that has left him impervious to threats of sanctions or international isolation, such that he shrugged off threats by members of the Group of 8 countries to boycott this year’s summit meeting in Sochi, Russia.

Because of Mr. Putin’s centralized authority, Russia’s policies and actions in moments of crisis can appear confused or hesitant until Mr. Putin himself decides on a course of action. That was the case in the days when violence erupted in Kiev, Ukraine’s capital, prompting a frantic effort by the Europeans to mediate a compromise. Mr. Putin, perhaps preoccupied with the Olympics, did not send a representative to those talks until the agreement was ready to be initialed.

Dmitri Trenin, the director of the Moscow Carnegie Center, said that Russia’s role in Ukraine’s upheaval was “very passive” up until the moment that the government of President Viktor F. Yanukovych collapsed. This was true, he said, despite the Kremlin’s wariness about any new Ukrainian trade agreement with the European Union and its pledge in December to provide a $15 billion package of assistance to shore up the country’s faltering finances. Jolted by the government’s collapse, Mr. Trenin said, the Kremlin “sprang into action almost immediately.”

He and other officials and analysts said that Mr. Putin’s reaction stemmed from the collapse of the agreement on the night of Feb. 21. Mr. Putin, by his own account at a news conference on Tuesday, warned Mr. Yanukovych not to withdraw the government’s security forces from Kiev, one of the demands of the agreement being negotiated.

“ ‘You will have anarchy,’ ” Mr. Putin said he told him. “ ‘There will be chaos in the capital. Have pity on the people.’ But he did it anyway. And as soon as he did it, his office and that of the government were seized, and the chaos I warned him about erupted, and it continues to this day.”

By then, however, Mr. Yanukovych had already lost the support of his party, whose members joined others in Parliament in ordering the security services off the barricades that they had maintained around government buildings in Kiev. Mr. Yanukovych, fearful because of reports of armed protesters heading to Kiev from western Ukraine, packed up documents from his presidential residence and fled in the early hours of the next morning. That night Mr. Putin was still assuring President Obama in a telephone call that he would work to resolve the crisis.