Anchored by Jake Tapper, The Lead airs at 4 p.m. ET on CNN.
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(CNN) – President Barack Obama spoke with Russian President Vladimir Putin on the phone this weekend for 90 minutes, but that wasn't enough to convince the former KGB colonel to pull his troops out of Ukraine's Crimean peninsula.
By late Sunday, Russian forces had complete operational control of the critical land mass. Vice President Joe Biden tried his own telephone diplomacy Monday, calling Russian Prime Minister Dmitry Medvedev to implore a peaceful withdrawal. But the answer, again, was "nyet."
Deputy national security adviser Tony Blinken joined CNN's "The Lead with Jake Tapper" ten days ago, when Obama had – again – just wrapped up a phone call with Putin.
"President Putin said he supported the agreement that was reached in Ukraine. And said he wanted to work cooperatively with us, with the Europeans, and the international monetary fund to create a support package for Ukraine. It was a very positive conversation," Blinken said of that call.
Did Putin lie to the president?
"I don't know if he lied, or if he changed his mind," Blinken told CNN today.
"The fact of the matter is, Russia has intervened militarily in the Ukraine, violating its integrity, violating its territorial integrity, and the President is now mobilizing the international community to support Ukraine, and isolate Russia for the actions its taken," said Blinken.
For more of our interview with White House official Tony Blinken, check out the video above.