Russia gave its clearest signal yet Monday that it plans to move fast to annex Crimea, defying U.S. and European threats of sanctions a day after a referendum in the breakaway Ukrainian region to secede passed handily.

The Moscow-backed leadership of Crimea wasted no time in formally asking to join Russia following the hastily called referendum in which 97% of voters supported becoming part of Russia.

“We will take care of our part quickly, quickly and responsibly,” Sergei Naryshkin, speaker of the lower house of Russia’s parliament, told reporters in response to the Crimean parliamentary vote, according to local news agencies. …

The Kremlin didn’t immediately specify what Mr. Putin’s message would be, but the official ITAR-Tass news agency said the address would cover “accepting Crimea into the Russian Federation.”