IN HIS last policy address as secretary of defense, Robert M. Gates joined a long list of his predecessors in lambasting European governments for failing to contribute adequately to the NATO alliance. Despite an ongoing war in Afghanistan and the growing threat from rogue states such as Iran, Mr. Gates noted, European defense spending has fallen 15 percent since 2001, even as that of the United States has doubled. The American portion of NATO defense spending, which hovered around 50 percent during the Cold War, is now 75 percent. While all 28 of the alliance’s members supported the current intervention in Libya, less than half have contributed forces to it and fewer than a third have participated in strike missions.

Mr. Gates rightly blamed European governments for being “apparently unwilling to devote the necessary resources or make the necessary changes to be serious and capable partners in their own defense.” He outlined “the real possibility for a dim, if not dismal, future for the transatlantic alliance.” And he offered three practical suggestions to avert disaster for Western defense: “making a serious effort to protect defense budgets from being further gutted;” “better allocating the resources we do have;” and “following through on commitments to the alliance and to each other.”

The secretary’s sermon was well-justified. But we couldn’t help wondering if the assembled European ministers would find some irony in his lessons. The Obama administration, after all, is pressing for big defense cuts of its own — up to $400 billion over the next dozen years, on top of savings of a similar amount already identified by Mr. Gates. That will mean, the Pentagon chief said in a speech last month, “a smaller military” that “will be able to go fewer places and do fewer things.”

The United States is participating in the Libya mission, but Mr. Obama withdrew U.S. strike aircraft and has refused to redeploy them despite appeals from Britain and France. The allies meanwhile are watching nervously as the Obama administration debates how large a withdrawal to make from Afghanistan this year — with some reports suggesting that senior White House aides are again pushing to abandon the mission of creating an Afghan government and army capable of defending the country by 2014. Mr. Gates said “there will be no rush for the exits”; but European leaders could be excused for wondering whether Mr. Obama will stick to the “commitments” that his defense secretary spoke of.

Mr. Obama’s policy in Libya appears aimed at compelling allies to take more responsibility for NATO missions. His defense cuts will still leave the United States with a larger share of its gross domestic product devoted to defense than any other NATO member. But it’s hard to see Europeans responding to appeals like that of Mr. Gates at a time when the United States is reducing its military capabilities, scaling back its objectives and insisting on taking a back seat during a war. It may be that NATO has a dim future, but if so it’s not only because its smaller members are shirking their responsibilities. It’s also because its dominant member leader is eschewing its indispensable role of leadership.