Defense Minister Urmas Reinsalu said on ETV's Foorum that letting Crimea slip away without a response would reinforce Russia's desires as an aggressor. A frozen conflict would also persist in such a case, said Reinsalu.

"It is certainly a painful lesson from the Georgia war as well," Reinsalu said. "If you ask whether the West has acted sufficiently forcefully in the broader sense, it hasn't. That error goes back to Georgia, where the aggressor saw that use of military force and sending in the tanks paid off.

"That's a question that is existential for us," he said.

Kadri Liik, a researcher with the European Council on Foreign Relations, told ETV's Terevisioon that Vladimir Putin knew no one wanted to fight a war with Russia. She, too, brought up the Georgian war of 2008, which she said ended relatively painlessly for Russia.

She said she agreed with Angela Merkel that Putin in some sense lives in his own reality and "Russia had started believing its own propaganda" about extremists taking power in Ukraine. 

Asked what the likeliest scenario was, Liik answered: "I think it will just smolder. Everyone has something to say about why it's bad, but no one can do anything. The best that can happen is that the West can show economic and political support for Ukraine's current government, and keep the rest of Ukraine together. It would be especially good if a contact group could be formed on Crimean topics - this has been discussed.

"Some legal mechanism where the West would be a participant could be established so that it just by Russia laying down the law by force but rather the conflict would remain bound to some extent by international treaties. That would give some ways to influence the conflict in future."