One prominent member of the council, Valentina I. Matviyenko, chairwoman of the upper house of Parliament, emerged from the meeting declaring that it was impossible that Russia would invade Crimea, yet a couple of days later Russian troops were streaming into the peninsula.

When Mr. Putin made his first public remarks on the crisis on Tuesday, he said that Russia would not support Crimea’s efforts to secede. On Friday, the Kremlin allowed a mass pro-secession rally in Red Square while senior lawmakers loyal to Mr. Putin welcomed a delegation from Crimea and pledged support to make it a new province of the Russian Federation.

An examination of the seismic events that set off the most threatening East-West confrontation since the Cold War era, based on Mr. Putin’s public remarks and interviews with officials, diplomats and analysts here, suggests that the Kremlin’s strategy emerged haphazardly, even misleadingly, over a tense and momentous week, as an emotional Mr. Putin acted out of what the officials described as a deep sense of betrayal and grievance, especially toward the United States and Europe.

Some of those decisions, particularly the one to invade Crimea, then took on a life of their own, analysts said, unleashing a wave of nationalistic fervor for the peninsula’s reunification with Russia that the Kremlin has so far proved unwilling, or perhaps unable, to tamp down…

“We shouldn’t assume there was a grand plan,” said Mark Galeotti, an expert on Russia’s security forces from New York University who is in Moscow and regularly meets with security officials. “They seem to be making things up as they go along.”