Military leaders warned Congress on Wednesday that steeper cuts in defense spending, as either a policy choice or a consequence of political gridlock, will gut the armed forces and sap U.S. global influence.

Their predictions of doom, while disputed by some private defense and foreign policy analysts, reflect a consensus Pentagon view that even as the U.S. winds down its military involvement in Iraq and Afghanistan it would be highly risky to national security to make large, across-the-board cuts in spending.

The chiefs of the Army, Navy, Marine Corps and Air Force testified that bigger budget reductions — beyond the $450 billion to $465 billion to which the Obama administration already is committed — would limit their ability to recover from 10 years of combat and undermine efforts to keep experienced troops.

Gen. Ray Odierno, the Army chief of staff, told the House Armed Services Committee in a rare joint appearance with his fellow service chiefs that a decade-long pullback in U.S. defense spending could cause potential enemies to question the credibility of U.S. military power and challenge U.S. interests.

Odierno said cuts of as much as $1 trillion would mean an "unacceptable" risk to U.S. national security.

"Cuts of this magnitude would be catastrophic to the military, and in the case of the Army would significantly reduce our capability and capacity to assure our partners abroad, respond to crises and deter our potential adversaries, while threatening readiness and potentially the all-volunteer force," Odierno said.

He and the other service chiefs argued sharper cuts in the budget could make it too costly to keep troops, ships and aircraft based abroad — what is known as the military's "forward presence." Without that presence, they argued, the U.S. would lose the ability to help other countries fight threats like terrorists.

The debate over defense budgets is just one aspect of a broader political fight over fixing the nation's debt problem during a presidential election season. It comes at what Defense Secretary Leon Panetta last week called a "turning point" for the military, with an uncertain outlook for tackling a wide range of security threats such as cyberattacks, terrorism, Iran's nuclear ambitions and China's rise.

The Defense Department's budget has nearly doubled to $700 billion in the 10 years since the Sept. 11 terrorist attacks. Those numbers do not include the trillion-plus spent on the wars in Iraq and Afghanistan.

A special bipartisan committee is now searching for agreement on at least $1.2 trillion in overall spending cuts over 10 years. If it fails to do so by Nov. 23 or if Congress rejects its plan, then automatic, across-the-board cuts of $1.2 trillion kick in, with half coming from defense. That would be in addition to defense cuts of $450 billion to $465 billion that have already been promised over the coming decade.

The supercommittee is so far showing little sign of progressing toward a deal.

Democrats have demanded higher taxes as their price for accepting significant savings from benefit programs such as Medicare, but have been rebuffed by Republicans who oppose tax increases.

At the House hearing, Gen. Norton A. Schwartz, the Air Force chief of staff, asserted that budget cuts beyond the $450 billion to $465 billion already in the works would cause severe, long-term damage to his service.

Schwartz sketched a desperate scenario in which steeper budget cuts would force across-the-board reductions in the way the Air Force functions and its ability to prepare for future crises and wars.

"Ultimately, such a scenario gravely undermines our ability to protect the nation," he said. "But beyond the manner in which the potential budget cuts are executed, even the most thoroughly deliberated strategy will not be able to overcome the dire consequences if cuts go far beyond the $450 billion-plus in anticipated national security budget reductions over the next 10 years."

The Navy's chief, Adm. Jonathan W. Greenert, said defense cuts of as much as $1 trillion would cause "irreversible" damage to the military.

Some private defense analysts say such reductions would not cause catastrophic damage.

Gordon Adams, a professor of international relations at American University and a former budget official in the Clinton White House, is a critic of what he calls misplaced fears about defense spending cuts.

"In fact, were defense budgets to decline by $465 billion from the current (Pentagon) projections, it would be the most moderate and shallow build down we have ever experienced since the end of the Korean War," Adams wrote in a blog post.

"So there is little reason to fear, little reason to cry 'doomsday' as we manage this build down," he added.

Gen. James F. Amos, commandant of the Marine Corps, told the House committee that steeper defense cuts would undermine the military's ability to maintain a large presence in key parts of the world. He argued that if the U.S. military were compelled to pull back, other countries such as China would fill the void.

Schwartz, the Air Force chief, made a similar argument.

"If we want to be a global power, we've got to be out and about," Schwartz said.


Robert Burns can be reached on Twitter at http://twitter.com/robertburnsAP