The foreign-policy establishment wants two things from NATO: the ability to retain outsized influence on European defense and foreign policy, and cheap deterrence of Russia. For decades, Washington’s NATO policy seems to have worked, or at least hasn’t failed. EU security cooperation has floundered, and Russia hasn’t militarily threatened any NATO member-state. But the Ukraine crisis raises questions about U.S. interests and the Russian perception of them.
The unanimity in Washington that there was no interest in fighting Russia over Ukraine could cause deterrence to fail where Washington has even smaller interests, such as the Baltic states. Putin could easily see that the U.S. interests in one of those countries are smaller than they were in Ukraine and decide to violate their sovereignty in spite of the NATO commitment. Given that no American political leader favored fighting for Ukraine, the only argument for fighting for a NATO member that is even less strategically important would be a sheet of paper.