WASHINGTON: Looming across-the-board budget cuts will present the U.S. military with the most significant readiness crisis in more than a decade unless quick action is taken to avoid the spending reductions, Defense Secretary Leon Panetta warned during testimony Thursday before the Senate Armed Services Committee.

If the billions of dollars in cuts are allowed to stand, Panetta said, he would have to throw the country's national defense strategy "out the window," and the United States would no longer be a first-rate power. "This will badly damage our national defense and compromise our ability to respond to crises in a dangerous world," Panetta said.

But Panetta assured lawmakers the Defense Department would take the steps necessary to deal with possible threats in the Persian Gulf region after he approved the Navy's request to halve its aircraft carrier presence in the area, from two carriers to one.

Anticipating the Defense Department will have less money to spend, Panetta said the Pentagon has already put in place a freeze on hiring and cut back on maintenance at bases and facilities. Those moves are reversible, he said, as long as Congress acts quickly to head off the cuts, known as sequestration, and approves a 2013 military budget.

The potential for sequestration is the result of Congress' failure to trim the deficit by $1.2 trillion over a decade. The Pentagon faces a $42.7 billion budget cut in the seven months starting in March and ending in September. The reductions through sequestration would be in addition to a $487 billion cut in defense spending over the next ten years mandated by the Budget Control Act passed in 2011.

Panetta said that the department understood that it needed to do its part to help deal with the federal deficit and has been working to adjust its plans to deal with the lower spending levels. But adding sequestration on top of that creates an untenable situation, he said.

Panetta, who is retiring soon from his post, has been leading a vocal campaign to stop sequestration because it would leave the military "hollow," meaning the armed forces would look good on paper but would lack the training and equipment they need to handle their missions.

As part of that campaign, the Defense Department has been providing greater details on the impact of the cuts. The department on Wednesday said it is cutting its aircraft carrier presence in the Gulf region, a move that represents one of the most significant effects of the spending cuts. The U.S. has maintained two aircraft carrier groups in the Gulf for much of the last two years.

The deployments of the USS Harry S Truman and the USS Gettysburg, a guided-missile cruiser, are being delayed as part of the Navy's plan to deal with the budget uncertainty.

Former Defense Secretary Robert Gates decided in 2010 to keep two carrier groups in the Gulf region as tensions with Iran escalated. Iran has repeatedly threatened to close the Strait of Hormuz, a strategic waterway through which roughly a fifth of the world's oil supply passes, in retaliation for increased Western-led sanctions.

"We're going to do everything we can to make sure that we are prepared to deal with the threat from Iran," Panetta said. "We will have one carrier there and we will deploy other forces there so that we can hopefully fill the gap."

Congress has not approved a defense budget for the 2013 fiscal year. Lawmakers have instead been passing bills to keep spending levels at the same rate as last year. That means the Pentagon is operating on less money than it planned for and that compounds the problem, Panetta said.

"We have got to end the cloud of budget uncertainty that hangs over the Department of Defense and the entire U.S. government," Panetta said.