* Gates vows not to repeat across-the-board cuts of '70s, '90s
* House panel clears $690 billion for military in 2012
* Strategy, not math, should drive budget plans, Gates says
WASHINGTON, May 12 (Reuters) - U.S. Defense Secretary Robert Gates said on Thursday his main goal before stepping down next month is to focus attention on strategic choices facing the nation as it flattens military spending to help curb the growing national debt.
He spoke hours after the House of Representatives Armed Services Committee authorized $690 billion for the U.S. military complex in fiscal 2012, including $119 billion to fund the war in Afghanistan and transition in Iraq.
The sum cleared by the committee for the year starting Oct. 1 represented a small increase from the current fiscal year. It is projected to be a high-water mark as the wars wind down along with a post-Sept. 11 military spending surge.
Gates told Marines at Camp Lejeune, North Carolina, that the issue involved tradeoffs between acceptable risks and defense capabilities that could be sacrificed.
"I am determined that we will not repeat what we did in the 1970s and 1990s, which is across-the-board cuts that end up hollowing out the force," he said.
Gates is to step down on June 30. While he did not offer specific recommendations on the military's future structure, he said he hoped to throw light on the choices at hand for President Barack Obama and other decision-makers, including his nominated successor as defense secretary, CIA director Leon Panetta.
"If you want to change the size of the budget in a dramatic way, what risk are you prepared to take in terms of future threats to the country?" Gates asked.
"How do you manage that risk as a part of a process of cutting the budget?" he added. "This is what I call strategy, not math. Right now the process is just the reverse. Everybody's doing math and not strategy."
Gates' warning followed several months of political brinkmanship over the fiscal 2011 federal budget, which ultimately funded the military complex at $668.6 billion compared to the $709 billion requested by Obama.
Pentagon leaders have cautioned against cutting too much too quickly, because rebuilding military capabilities in the future will be even more expensive.
On Wednesday, Deputy Defense Secretary William Lynn sounded a similar theme at an investors' conference in New York, stressing the need to pare back to essential missions while maintaining a healthy defense industrial base.
The House bill for 2012 added $425 million aimed at continuing the production line for the Army's M1 Abrams tanks, a General Dynamics Corp (GD.N) program, and M2 Bradley fighting vehicles, made by BAE Systems Plc (BAES.L).
The plan currently advocated by the Army would result in the first break in tank production since 1941, lasting one to three years.
Roscoe Bartlett, chairman of the subcommittee that overseas tactical air and land forces, argued that such a gap could end up costing more than keeping Abrams tank and Bradley fighting vehicle production lines going while preserving important parts of the U.S. military industrial base.
The House panel voted 54-to-5 Wednesday to require the Pentagon to let General Electric Co (GE.N) and Rolls-Royce Group Plc (RR.L) continue development of their alternate engine for the F-35 fighter as long as it was done at no cost to the government, despite the Pentagon's formal cancellation of its competitive engine program for the fighter last month.
The Senate Armed Services Committee is expected to take up its version of the National Defense Authorization Act next month. The two versions must be passed by the full House and Senate and any differences must be ironed out before being sent to Obama for his signature into law.
Obama is pressing to trim $400 billion, or 4 percent, from roughly $10 trillion in projected national security-related spending through fiscal 2023 as part of the debt reduction drive. (Editing by David Lawder)