MOSCOW — President Vladimir V. Putin of Russia has publicly indicated for the first time that the planning to reclaim Crimea from Ukraine started weeks before the Crimean referendum on the issue, which he had cited repeatedly as the main reason for Russia’s annexation.

Mr. Putin said he made the decision around 7 a.m. on Feb. 23, 2014, after an all-night emergency meeting with his security chiefs on the crisis in Ukraine. Viktor F. Yanukovych had just been deposed as the president of Ukraine, and the meeting was called to discuss his rescue, Mr. Putin said.

Russia has long contended that it acted spontaneously to reclaim Crimea, mainly to protect Russian speakers who it said had been threatened, and to stave off what it suspected was an attempt by NATO to colonize the Black Sea.

Mr. Putin in particular has emphasized the role of the March 16 referendum in which an overwhelming majority of Crimeans voted to rejoin Russia.