Last Friday, in a tough-minded speech delivered in Brussels, Secretary of Defense Robert Gates told NATO that money talks, and unless European members cover their fair share of alliance defense costs, America may walk.

Over the last five decades, numerous American leaders have faulted our European allies for failing to meet agreed-upon alliance defense commitments. Gates' critique, however, was extraordinarily direct.

"The blunt reality," Gates told the audience of NATO ambassadors, "is that there will be dwindling appetite and patience in the U.S. Congress -- and in the American body politic writ large -- to expend increasingly precious funds on behalf of nations that are apparently unwilling to devote the necessary resources or make the necessary changes to be serious and capable partners in their own defense."

Gates is retiring, which positions him to play bad cop and excoriate European slackers for years of defense neglect. The bad cop said Americans can read financial reports. America accounts for three-quarters of NATO's combined defense spending, hence the dwindling appetite for supporting NATO on a budget as usual basis even among committed Atlanticists. Gates' likely successor as secretary of defense, Leon Panetta, can play good cop in future alliance discussions, seeking collective compromise with a softer voice.

But compromise may be difficult. An ugly fact -- the enormous American and European debt burdens -- underlies Gates' blunt reality.

Debt saps America, and everyone knows it. Liberal Democrats are loath to cut entitlement spending, yet the realists among them accept it as inevitable. Trimming defense spending makes entitlement cuts more politically palatable to their constituencies.

The Obama administration wants the Pentagon to slice its budget by approximately a half trillion dollars over the next dozen years. There is Republican support for curbing defense outlays, as well -- the debt is a strategic threat. Many Americans believe Europeans have shirked their defense duties and milked U.S. taxpayers. The Europeans let dollars buy the bullets while their Euros support social welfare programs.

Dollars have bought the bullets, bombs, intelligence platforms, tanker aircraft, specialized planning capabilities and other combat sustaining assets that make NATO's Libyan war possible. In his speech, Gates mentioned that the Libyan war had revealed serious "shortcomings, in both capability and will, that have the potential to jeopardize the alliance's ability to conduct an integrated, effective and sustained air-sea campaign."

Afghanistan has revealed the same European shortcomings. Once upon a time, all 28 NATO members committed themselves to spending 2 percent of their gross domestic product on defense. According 2010 data, France, Great Britain, Albania, Greece and the U.S. met the commitment, but since then Greece has slashed defense spending.

 European members point to their own current economic crises, with Greece the nightmare case, but Spain, Portugal and Italy are also battling potential bankruptcy and default. This, too, is blunt reality.

Gates, in what amounted to a plea for foresight despite current fiscal woes, put Europe's failure to meet alliance commitments in historical and generational contexts. "If current trends in the decline of European defense capabilities are not halted and reversed, future U.S. political leaders -- those for whom the Cold War was not the formative experience that it was for me -- may not consider the return on America's investment in NATO worth the cost."

Massive debt and economic recession, combined with a lack of foresight and lack of leadership, may achieve what the Soviet Union could not: the destruction of NATO.

The loss of NATO, however, would leave a tremendous void. As a political network as well as military alliance, NATO has served Europe, Canada and the U.S. very well. Despite the numerous obituaries for the organization -- many written after the Berlin Wall cracked in 1989 -- NATO did not die. The pundit undertakers underestimated NATO's political value and as a result woefully misjudged its post-Cold War resilience.

Today, Russia remains unstable. Iran's dictators seek nuclear weapons. 2011's Arab Spring has jolted the world. NATO connectivity is a bulwark against uncertainty.

Secretary Gates understands this. Hence his warning -- and lamentation.