By Andrea Shalal
WASHINGTON (Reuters) - Top U.S. defense officials are bracing for a brutal season of budget negotiations, warning U.S. lawmakers that the U.S. military will gradually become unable to respond to emerging crises if Congress blocks the Pentagon's plans to cut military compensation, close bases and retire entire fleets of aircraft.
Senior officials have also begun mapping out in stark terms what additional weapons and capabilities will be sacrificed if Congress does not reverse mandatory budget cuts that are due to resume in fiscal 2016 under a process known as sequestration.
Air Force Undersecretary Eric Fanning told reporters on Tuesday other programs would have to be cut if Congress blocked the service's plan to retire both its U-2 spy plane fleet and its fleet of A-10 Warthog planes for close air support.
"In my view, we can't cut into readiness far enough to cover keeping those two fleets. Something would have to give," he said.
He said the Air Force faced big bills in coming years for its three top priorities: Lockheed Martin Corp's F-35 fighter jet, a new long-range bomber, and Boeing Co's new tanker to refuel fighter jets in mid-air.
Chief of Naval Operations Admiral Jonathan Greenert told reporters late on Monday that the Navy would have no choice but to curtail funding for a planned refueling of the nuclear-powered USS George Washington aircraft carrier if sharp cuts in military spending remained in effect for 2016 and beyond.
Such a decision, he said, would have a big impact on the shipbuilding industrial base, noting that the refueling involved several hundred thousand man-days of work, and could affect the ability of carrier building Huntington Ingalls Industries Inc to build the next aircraft carrier.
Huntington Ingalls, General Dynamics Corp, Lockheed, Boeing and other weapons makers are each lobbying to maintain or increase funding for their programs, warning that big cutbacks will be especially hard on smaller suppliers.
Greenert said the Navy had included money in the fiscal 2015 budget to get the carrier ready for de-fueling beginning in September 2016, something that will have to happen regardless whether the ship is ultimately retired or refueled.
If Congress blocked those plans - which the Navy estimates would save $7 billion - the Navy would be forced to reduce its orders of submarines and destroyers instead, he said, noting that it would be hard to find big enough cuts elsewhere.
Greenert said the Navy still had a requirement for 11 carriers, but had been forced to make tough choices in its fiscal 2015 budget as it tried to balance competing priorities, including the need to start work on a replacement for the Ohio-class submarines that now carry nuclear weapons.
Greenert is due to testify before the House Armed Services Committee along with Navy Secretary Ray Mabus and Marine Corps Commandant General James Amos on Wednesday.
Lawmakers are already resisting specific proposals in the Pentagon's budget plan, often based on their interest in preserving jobs in their home districts. But they have also said they don't expect lawmakers to agree on other deficit reducing measure that could allow them to end sequestration.
Army General Martin Dempsey, chairman of the Joint Chiefs of Staff, last week told lawmakers he knew the proposed reforms were "unpleasant and unpopular" but the department urgently needed to cut its overhead to keep pace with growing threats.
He appealed to lawmakers to allow the Pentagon to cut infrastructure, slow the rate of growth in military pay and retire older weapons so it could invest in new technologies.
"We simply can't ignore the imbalances that ultimately make our force less effective than what the nation needs," he told the Senate Armed Services Committee last week. "Kicking the can down the road will set up our successors for an almost impossible problem. We have to take the long view here."
Byron Callan, analyst with Capital Alpha Securities, said the Pentagon's Quadrennial Defense Review made it clear that the biggest threat facing the U.S. military was not China or some other military power, but dealing with the budget cuts.
He said military officials had thus far failed to explain in clear terms what effect the budget cuts would have on the military's ability to respond to military conflicts or disasters like the disappearance of a Malaysian airliner.
"The bottom line is that we won't be able to do some of the things that we're accustomed to doing," he said, noting that fewer military assets would invariably lead to higher casualty rates and potentially longer military conflicts.
Given continued uncertainty about future budget levels, top Pentagon leaders have told the services to once again prepare two alternate budgets for fiscal 2016 - one that reflects the mandatory budget cuts, and another that adds about $115 billion of funding as proposed under the five-year plan through 2019.
(Additional reporting by David Alexander; Editing by Ryan Woo)