For decades, the United States has supplied much of the military muscle in NATO. The strength of that force enhanced the security of Europe even as European nations slacked off military spending. Result: The U.S. far outspends all its NATO allies combined on defense.

Into this tidy European alliance tromps Russian President Vladimir Putin. With astonishing swiftness he has grabbed Russian-centric Crimea from the Western-leaning government of Ukraine. He won’t let go.

Putin’s aggressive move has rightly unsettled Russia’s NATO neighbors in Europe. They — and their allies in Washington — wonder, what’s next? Everyone is scrambling to prevent Putin from moving forces into Ukraine’s eastern territory.

The most powerful leverage against Putin isn’t in Washington, even though President Obama announced Thursday a new set of economic sanctions targeting Russian tycoons. This is Europe’s moment to punch back or … duck.

Germany is a major trading partner. Russia does much business in Great Britain, France, and across Eastern Europe. These NATO allies, acting with resolve and Washington’s help, could inflict serious economic pain by focusing sanctions on Russia’s vital energy industry. Revenues from energy have propped up the Putin government and Russia’s struggling economy. Other trade restrictions could dry up capital markets and make it harder for Russia to obtain the equipment and expertise it needs for the exploration and development of its untapped energy reserves. Travel restrictions should make it hard for Russia’s government and oligarchs to do business abroad.

The Europeans, however, are — unsurprisingly — divided. Many don’t want to lose Russian business. They don’t want to invite Russian retaliation, since many European countries depend on Russian oil and natural gas. They don’t want to rock the boat too hard.

You can be sure that Putin, a master strategist, is counting on European disarray.

This is Europe’s moment to carry its weight in the NATO alliance and inflict painful sanctions on Russia, even if the repercussions hurt at home.