"Moreover, unlike European gas companies, the big Russian players have much tighter ties with the state. If Moscow wants them to keep their share in the European market for strategic reasons, it may be able to make them do that. Russia would lose money — an important piece of geopolitical harm — but its leverage wouldn't be slashed," he said.
Vali Nasr, dean of the Johns Hopkins School of Advanced International Studies, says however, that American supplies could have an effect.
"America's gas would be more expensive than Russia's, but the mere fact of an alternative would sap Russia's leverage to blackmail Europe with threats of price rises or cutoff," he writes in The New York Times.
Nevertheless, Michael McFaul, the just-departed U.S ambassador to Moscow, says the availability of American gas to Europe "puts pressure on the government inside Russia if suddenly they're losing those markets."
But, he said, "I want to emphasize this is not going to happen overnight, over years, if not decades, not in days and weeks... "
So the United States can't do much on the natural gas front right now, but it will become a lever Washington can pull in future crises with Moscow. Given Putin's recent behavior and his drive to bring former Soviet republics back under Moscow's sway, there seems little doubt those future crises will arise.
The long view might be what prompted the ambassadors to Washington from Hungary, Poland, Slovakia and the Czech Republic to write over the weekend to John Boehner, Speaker of the U.S. House of Representatives, urging the U.S. to increase natural gas exports to ward off shortages if the Russians cut off supplies, even though Boehner needs little convincing.
The ambassadors pushed for quick approval of natural gas exports, saying the "presence of U.S. natural gas would be much welcome in Central and Eastern Europe. All four countries were invaded by Soviet forces or place under martial law during reform movements before the Soviet empire collapsed in 1991.
They had a sympathetic ear in Boehner, who wrote in the Wall Street Journal last week: "The ability to turn the tables and put the Russian leader in check lies right beneath our feet, in the form of vast supplies of natural energy."
But the White House argues Russia is so dependent on revenue from gas sales that it is unlikely that the Kremlin will cut off supplies to Europe regardless of the Ukraine crisis.
"Proposals to try to respond to the situation in Ukraine that are related to our policy on exporting natural gas would not have an immediate effect," White House spokesman Josh Earnest said.