Defense Secretary Chuck Hagel rejected the suggestion that President Barack Obama tapped him to “cut the heart out of the Pentagon,” pointedly reminding lawmakers Thursday that Congress approved the smaller, deficit-driven military budgets long before he took the job.

Faced with a $487 billion budget cut over a decade, Hagel and Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, said the Pentagon had no choice in drawing up the politically unpopular reductions in the president’s proposed $526.6 billion budget for next year.

The blueprint calls for another round of domestic base closures, higher health care fees for retirees and their dependents, and a smaller pay raise for personnel. Dempsey cast the choice as between a well-compensated force and the readiness of the nation’s war fighters.

Cost-conscious lawmakers have clamored for fiscal austerity in a period of trillion-dollar deficits but often balk when the cuts hit military bases in their home states or affect powerful veterans’ groups. That disconnect was on stark display during the nearly four hours the Pentagon leaders testified before the House Armed Services Committee.

In one exchange, Rep. Mac Thornberry, R-Texas, questioned Hagel on what his role is — managing the decline in defense spending or warning of the dangers of military cuts.

“There is a widespread view that you were brought into the Pentagon to cut defense,” Thornberry told Hagel.

The secretary, on the job six weeks, said the cuts were law, part of the budget agreement reached between Obama and congressional Republicans in August 2011. Added to those reductions are $41 billion in automatic, across-the-board cuts, commonly known as sequestration.

Military leaders have warned that the automatic cuts would do harm to the military, but deficit hawks in Congress prevailed over defense hawks and the cuts kicked in March 1. Tea partyers, Republicans and Democrats continued to disagree over whether to reverse them.

“I can’t lead my institution into a swamp of knife fighting over protesting what’s already in place,” Hagel told the committee.

The hearing underscored the difficulty the Pentagon faces in persuading Congress to accept what it says are cost-saving steps.

Republicans and Democrats on the panel criticized any additional base closings, arguing that the upfront costs were too high. Hagel said the base closing system was “imperfect,” but argued it was a “comprehensive and fair approach” that would result in considerable savings in the long term.

The Pentagon has proposed $2.4 billion over five years to cover the initial costs of closings, set the round for 2015 and indicated that the closures would not be implemented until a year after that.

Hagel, along with his two predecessors — Robert Gates and Leon Panetta, have called for increased fees for military health care, especially for retirees under the age of 65. The leaders pointed out that those in the TRICARE program once paid 27 percent of health care costs. Now their cost is 11 percent.

The overall health care program is some $50 billion and accounts for 10 percent of the Pentagon budget. The Congressional Budget Office estimates the cost could reach $65 billion by 2017 and $95 billion by 2030.

But several Republicans and Democrats on the committee, including Rep. Joe Wilson, R-S.C., chairman of the military personnel subcommittee, dismissed the notion of raising fees.

Rep. Adam Smith of Washington state, the committee’s top Democrat, summed up the difficulty for the Pentagon.

“There are places where we can cut the defense budget that will not affect our national security, that Congress rather consistently stops you from doing,” he told Hagel.