"I don't think anyone can say with real certainty what Mr. Putin's end game is," he said, in an interview. Haass said neither side wants an escalation but it's unclear whether Putin is seeking more influence over affairs in Ukraine, to take control of Crimea or to seize all of Ukraine.
Whatever the outcome, the situation is focusing attention on Russia's energy relationship with Europe.
Europe receives about 3.5 billion barrels a day of oil from Russia, but the bigger issue is about half the gas heading for Europe from Russia goes through the Ukraine.
(Read more: It's time to export 'abundance' of US oil: Senator)
The Ukraine is an important gateway for Russian gas transmission to Europe and elsewhere, but Russia has been moving to reduce its dependence on the country. Gas is also a major source of friction between Russia and Ukraine, which owes Russia billions.
"A decade ago, Ukraine played the same role it does now. It's the gateway for gas. It did the same for oil," said Matt Sagers, senior director Russia and Caspian Energy at IHS.
Haass said if the U.S. moves toward energy sanctions against Russia, it could consider putting more U.S. oil on to the world market to ease prices.
"I was in favor of opening the export spigot before this," he said.
Separately, Kevin Book, managing director of ClearView Energy Partners, said in a note that the energy relationship with the West may actually act as a brake on both Western governments and Russian actions.
(Read more: 'Nazis' and 'Hypocrites': What Russia's saying on TV)
"This Russian conflict with Ukraine may have more to do with Cold War-style force projection than natural gas pipelines, but several energy policy implications stand out nonetheless. First, the E.U.'s dependence on Russian natural gas may constrain Western actions, but Russia has its own compelling commercial reasons to keep gas flowing.
Second, Europe has few near-term alternatives to Russian gas, but the set of medium-to-long-term options goes beyond U.S. LNG. Finally, political challenges and economic realities may limit the extent to which U.S. LNG can offer Europe a supply diversification solution," he wrote.
—By CNBC's Patti Domm. Follow her on Twitter