Fmr. Bush national security adviser: We should have sanctioned Russia after Georgia invasion

(CNN) – President Barack Obama and Russian President Vladimir Putin talked for an hour Thursday afternoon, with the U.S. president stating "Russia's actions are in violation of Ukraine's sovereignty" and that there is a diplomatic way out, according to the White House.

The call came on the heels of Obama announcing sanctions, and telling reporters that a proposed referendum in Ukraine's Crimea region – one that, as proposed by proposed by pro-Russian Crimean lawmakers, would ask residents whether Crimea should be part of Ukraine or Russia – would "violate the Ukrainian constitution and violate international law."

"Our cranking up of pressure has really lagged events," said Stephen Hadley, former national security adviser under President George W. Bush

In an interview with CNN's "The Lead with Jake Tapper," Hadley laid out what will likely happen in the next ten days: There will be a referendum in Crimea, the population will vote to join Russia, and the Russian Duma will facilitate the entry into the Russian federation.

"That's where we're headed, and all this talk about off-ramps, I think it's pretty clear Putin doesn't want an off-ramp, he has decided to gobble up Crimea," said Hadley.

But while experts and analysts forecast that Russia will inevitably take Crimea, Hadley said the U.S. should never accept the legitimacy of the referendum, and work to strengthen the Ukrainian government economically any way it can – steps the Obama administration is already taking.

"What we need is an on-ramp. I think we need to re-commit to NATO, recommit to the security in Europe," said Hadley.

The U.S. also has to punish Putin, says Hadley, "to show that the strategic cost of what he's done outweighs the benefits, because the goal here is to keep him from doing it again in some other place."

"He's got (a modus operandi) now, he tries to win these countries over, he tried to win over Georgia, he tried to win over Ukraine. If he cannot do it, he gobbles up a piece of the country," said Hadley.

But when Russia invaded Georgia, Hadley was serving as national security adviser, and the Bush administration reacted in a similar manner to the Obama administration's response to the crisis in Ukraine. While he says they did a lot of things right, Hadley said there were a couple missteps.

"There were two mistakes made, one by us, one by the Obama administration. We did not use economic sanctions, partly because economic sanctions are much more sophisticated than they were," said Hadley.

"And secondly, the Obama administration did the reset too soon. We should have impose economic sanctions, and that should have been allowed to isolate and hurt Russia for a longer period of time before we got back into business," said Hadley.