Gates blasts European allies over NATO inaction (VIDEO)

In a sharp rebuke of America's European allies, Defense Secretary Robert Gates on Friday said NATO had a "dismal future" unless it boosted military spending and did more in the world's trouble spots.

In his final policy speech as Pentagon chief, Gates said the U.S. is losing patience with having to fight Europe's wars.

He cited Libya as an example: "The mightiest military alliance in history is only 11 weeks into an operation against a poorly armed regime in a sparsely populated country, yet many allies are beginning to run short of munitions, requiring the U.S., once more, to make up the difference."

Against a backdrop of a painful $1.4 trillion U.S. deficit, Reuters reports, Gates warned that U.S. lawmakers might begin to question the 75 percent share that Washington paid in NATO defense spending.

"The blunt reality is that there will be dwindling [U.S.] appetite and patience … 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 said.

"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."

Gates, in Brussels on the final day of an 11-day overseas trip, said NATO-led operations in Afghanistan had also exposed significant NATO shortcomings.

He said that despite having more than two million troops in uniform, non-U.S. alliance members struggled to sustain 25,000 to 45,000 troops in Afghanistan, "not just in boots on the ground, but in crucial support assets such as helicopters, transport aircraft, maintenance, intelligence, surveillance and reconnaissance."

"This … bodes ill for ensuring NATO has the key common alliance capabilities of the future," Gates said. "To avoid the very real possibility of collective military irrelevance, member nations must examine new approaches."

According to the AP:

Gates has made no secret of his frustration with NATO bureaucracy and the huge restrictions many European governments placed on their military participation in the Afghanistan war.

He ruffled NATO feathers early in his tenure with a direct challenge to contribute more front-line troops that yielded few contributions.

Gates steps down on June 30, to be replaced by Leon Panetta.