NATO can be proud of the role it played in supporting the overthrow of Libya’s murderous dictator, Col. Muammar el-Qaddafi. But the alliance’s own confidential assessment, reported in The Times on Sunday, pointed out that European members, who were among the first to call for military action, could never have pulled it off without extensive American involvement.

The Libya campaign was supposed to be a demonstration of European leadership. But even Europe’s most sophisticated militaries lacked the specialized aircraft and trained personnel needed to intercept Libyan government communications and verify potential targets, and they quickly ran short of precision-guided munitions.

The Pentagon stepped in to provide what Europe could not. But that experience is one more reminder that Europe is still not ready for prime time — and, no matter how important the stakes, European militaries are unable to conduct sustained air operations on their own, even in their own neighborhood. Without urgent efforts to remedy these shortcomings, NATO faces a bleak future of military marginalization and trans-Atlantic rancor.

Europe has never shouldered its fair share of NATO’s collective military burden. But, while Washington and the American taxpayer were prepared to put up with such free-riding during the cold war, patience is running out. Last year, the United States devoted 4.8 percent of its gross domestic product to military spending. European NATO members averaged only 1.6 percent. While the Pentagon needs to be far more disciplined in its own spending, the Europeans need to spend more on their militaries and spend it more rationally.