I don't really think the Germans will be bullied by our promise of gas. They have NEVER had any domestic gas/oil industry anyway, and have always seemed able to acquire enough for their needs... and they have the money to provide it regardless... again, I don't think the Germans will be open to that argument. And I am totally sure, that they understand the history of the region much better than we do.
This is what happens when a nation of intelligent people learn to practice our democracy.
Please look into the history of the Crimea... as much as we may hate Putin, Russia's claim to that particular piece of land is backed by historical precedent, let alone the majority of the folks that actually live there.
It is not worth spending American dollars and lives to stop this just to mollify McCain and the wingnuts.