The Senate Appropriations defense subcommittee voted Tuesday to freeze basic Pentagon spending next year to the 2011 level of $513 billion, cutting about $26 billion from President Obama’s original request for fiscal 2012.

With an additional $117.8 billion to fund the wars in Afghanistan and Iraq, the panel voted on a total of $630.8 billion — $18 billion below the amount the House passed in July.

The panel’s action must be approved by the full Appropriations Committee, which will take up the measure Thursday, and then by the Senate. But the move is in line with $350 billion in decreased military spending over the next 10 years that was called for by the federal debt-limit agreement in August.

Sen. Daniel Inouye (D-Hawaii), chairman of both the subcommittee and the full Appropriations Committee, said in a statement that despite the cuts, the bill “takes care of our men and women in uniform and their families, fully supports military readiness, protects the forces and maintains our technological edge.”

Part of the impetus for Congress to accept this level of reduced defense spending comes from another element of the August agreement. If a bipartisan “supercommittee” does not find at least $1.2 trillion in further reductions in overall government spending, or if Congress does not pass the committee’s recommendations, one result would be deeper and further across-the-board cuts of $800 billion or more in national security spending, most of which would have to come out of the Defense Department.

In testimony Tuesday before the supercommittee, Douglas W. Elmendorf, director of the Congressional Budget Office, said an analysis by his office showed that spending limits placed in the August agreement would cut defense outlays “by about $450 billion,” or deeper than originally expected. He added that such a cut “would probably lead to reductions” in the size of the military.

In marking up the fiscal 2012 spending bill, the Senate subcommittee approved a 1.6 percent pay raise for military personnel and added $230 million for shortfalls in the amounts sought for military personnel after the budget was submitted.

Among the cuts was $5 billion because of planned troop reductions in Afghanistan next year; $1.6 billion from “overstated requirements” for Afghan Security Forces training; $1.5 billion that the Pentagon said in June it didn’t need; and $695 million from the F-35 Joint Strike Fighter program.

In addition, reductions were made in nearly 600 programs because of such things as scheduling delays, program changes, inadequate justification and poor fiscal discipline, the panel said.

Although the panel was approving reductions, Ashton Carter, Obama’s nominee for deputy defense secretary and the current defense undersecretary for acquisitions, was telling the Senate Armed Services Committee about the danger that would arise from additional cuts, should the supercommittee fail. In prepared answers to questions for his confirmation hearing, Carter wrote that a further 10-year $800 billion reduction would lead to “the risk of hollowing out the force, and weakening our ability to respond to threats around the globe will go up significantly.”

Meanwhile, defense contractors are stepping forward to press their case against reductions. Top officers from Boeing, Pratt & Whitney and other companies are scheduled to hold a news conference Wednesday to discuss the “devastating job losses, national security threats and infrastructure implications that would result from budget cuts put in motion by this summer’s debt-ceiling deal,” according to a statement from the Aerospace Industries Association.