Is NATO strong enough to deter a Russia-Europe war?

Three decades ago, at the end of the Cold War, NATO members looked feverishly to find a mission to replace the then-defunct need to prevent the Soviet Union from invading Europe.

NATO’s dilemma was encapsulated in the phrase “Out of Area or Out of Business.” That is, having been freed from the Soviet threat, the alliance ought to provide protection and stability and promote democracy beyond its European boundaries.

The idea led NATO, in whole or in part, to a series of out-of-area wars—first in tumultuous Bosnia and Kosovo, then further afield in Afghanistan, Iraq and Libya. All exposed the possibilities of unified action while opening new divisions over just how far the alliance should reach beyond its own frontiers.

Thanks to Russian President Vladimir Putin and his 2022 invasion of Ukraine, NATO’s out-of-area debate has been pushed aside and replaced by a return to the alliance’s original raison d’etre: defense of allied Europe.

The reaffirmation of NATO’s original purpose has nonetheless exposed a disturbing reality: In the face of a possibly open-ended and particularly vicious conflict in Ukraine, the alliance’s nuclear deterrent may not be enough of a deterrent to protect the continent from spillover aggression.

Putin had upended the notion that mere possession of nuclear bombs and the ability to deliver them is not enough to prevent conventional warfare.

Instead, Russia is showing that possession of a nuclear arsenal can provide cover for invading a sovereign nation with only conventional arms. Putin has repeatedly threatened to use tactical nuclear weapons in Ukraine to restrain Western support for Kiev’s defensive war effort.

This reality is driving NATO’s broadest changes in its operations in years. Shortly