United States in attacking Bashar al-Assad's regime in Syria in 2013. But when US President Barack Obama walked back from his own "red line" over the regime's use of chemical weapons against Syrian civilians and deferred military action, Europeans decided that they could not act alone.

European leaders cannot simply tend a garden at home while the wilderness around them burns; they must pursue a shaping strategy to the south that addresses the conflicts producing both domestic terrorism and a refugee crisis that threatens to overwhelm their own citizens' tolerance. This is also true of the crisis to Europe's east, where the Russian invasion of Ukraine was precipitated by a decision by Ukrainian leaders to pivot west toward Europe and away from Moscow's embrace. Russian forces regularly challenge NATOdefenses. The wolf is at the door, yet most European nations still do not meet the NATO standard of spending 2 percent of GDP on defense.

By default, this leaves European security mainly in the hands of the Americans, whose military spending accounts for three-quarters of the NATO total. The US security guarantee has created a cocoon in which Europeans constructed an economic and political union while neglecting dangers from without and within.

To get a grip on the multiple security crises, European leaders must return to the world of great power competition. This does not mean a rerun of military mobilization, in the style of "Guns of August" and the early onslaught of World War I. It does mean expanding national and joint capabilities and demonstrating strategic initiative to