* Army chief says cuts jeopardize ability to fight a major war
* Warnings come as Congress squares off over 2014 spending
* Effective planning requires budget stability- Air Force nominee
By David Alexander
WASHINGTON, Sept 19 (Reuters) - With U.S. lawmakers spoiling for another fight over federal spending ahead of the new fiscal year next month, senior Pentagon officials are trekking to Congress with a sobering message: budget uncertainty is wreaking havoc with the armed forces.
The top U.S. military officers and senior defense officials warned in separate hearings this week that annual budget gimmickry plus across-the-board spending reductions of $50 billion are forcing them to cut back in ways that leave much of the military poorly trained and unready to respond in a crisis.
General Ray Odierno, the Army chief of staff, told lawmakers on Wednesday that if the military has to fully implement nearly $1 trillion in spending cuts over the next decade as envisioned by law, the Army may not be prepared to fight a long war.
"In my view, these reductions will put at substantial risk our ability to conduct even one sustained major combat operation," he told the Armed Services Committee in the U.S. House of Representatives.
Deborah James, President Barack Obama's nominee to be Air Force secretary, told the Senate Armed Services Committee on Thursday the problem was not only the size of the cuts, but the uncertainty of the congressional budgeting process as well as the across-the-board nature of some reductions.
Under current law, the Defense Department is cutting about $500 billion in projected spending over the next decade through its regular budgeting.
In addition, it faces $50 billion a year in spending reductions under a mechanism known as sequestration, which applies a flat percentage cut to every budget item that exceeds a spending cap, regardless of strategic import.
TOUGH TO PLAN
Spending fights in Congress add additional uncertainty to the Pentagon budgeting process, officials said.
Last year Congress funded the government for nearly half a year by means of a continuing resolution, which extended funding at the levels of the previous year. The process, likely to be repeated again this year, created a mismatch between spending needs and funding levels, plus it prevented the services from beginning new projects.
"Trying to plan for the future is incredibly difficult and enormously time-consuming when you are planning ... for different scenarios," James said, adding that she hoped the government could reach a deal to lift sequestration and give the services a better budget number.
"We would like to know what we are really executing for and planning for and have a greater degree of certainty than what has been the case," James said.
While Pentagon officials voice concern about the scale of the spending cuts, they are particularly worried about the speed of the reductions as a result of sequestration.
Achieving savings through a balanced reduction of the force size and eliminating excess capacity takes several years. To achieve immediate savings, the military is forced to cut from current spending for training and maintenance, leaving the services ill-prepared for a crisis.
The top military officers painted a grim picture of the impact of cutting $1 trillion in defense spending.
While the services have emphasized that troops preparing to deploy to Afghanistan would be fully trained, Odierno said that 85 percent of the Army's active and reserve combat units would be unprepared to fight after another year's worth of cuts.
Cuts beyond the 2014 fiscal year would jeopardize the Army's new weapons programs and further erode training for soldiers, he said. The Army would rebuild readiness between 2018 and 2023, but most likely by reducing the size of the active army to 420,000, about 70,000 fewer troops than current envisioned.
Admiral Jonathan Greenert, the chief of naval operations, said further cuts meant the Navy would be able to deploy one carrier strike force in the Pacific, one to the Arabian Sea and maintain only one at home to rush forward in an emergency.
Ordinarily the Navy has three carrier strike groups at home that it can send overseas in a crisis. Over the long run, the Navy's fleet size would fall to 255 ships in 2020, versus its current plan for 306, he said.
General Mark Welsh, the Air Force chief of staff, said he would have to reduce pilot flying hours by 15 percent due to the 2014 cuts and curtail or cancel major exercises. Over the long term, the service would have to cut about 25,000 airmen, about 4 percent of the total, and eliminate 550 aircraft, about 9 percent of the inventory.
General James Amos, the Marine Corps commandant, said he would have to cut the size of his force by 8,000 Marines to a total 174,000, a number he said was the smallest that could effectively go to war and conduct other ongoing operations.