Getting to a middle ground may be tough this year with the U.S. facing more than $15 trillion in debt as well as a political atmosphere in which compromise "is seen as a dirty word," Sabato said.

Deficit, Debt

The developing slowdown in defense outlays has taken place in the midst of a contentious debate over the federal deficit, ballooning debt, spending and taxes.

In an effort to get a grand compromise last year, Congress passed the Budget Control Act of 2011, which required cuts of $487 billion from projected U.S. defense spending for the decade ending 2021. If a so-called supercommittee failed to get an agreement on how to reduce the deficit and debt, an additional $500 billion would have to come out of defense.

Those prospective cuts were seen as an incentive to get Republicans to compromise. The supercommittee couldn't agree, and the cuts are scheduled to take place starting in January.

Although McKeon, the House Armed Services chairman, supported the law, "he has come to regret that vote and is having buyer's remorse," said Tom Donnelly, a defense analyst at the American Enterprise Institute in Washington.

McKeon has said adding $4 billion to the Pentagon's 2013 budget request would keep ships the Pentagon wanted to retire and slow reductions in Marine Corps and Army forces. Those measures would ensure "the president's new defense strategy is not a paper tiger," McKeon said at a May 9 committee meeting.

Protecting 'Constituencies'

Defense Secretary Leon Panetta shot back at McKeon, saying the money added by the House is an attempt by Congress to "protect particular constituencies."

The Obama administration released a national security blueprint in January that the Pentagon has said would result in a smaller military over the next 10 years following the end of the wars in Iraq and Afghanistan.

The military services would decline to 1.32 million members on active duty by 2017, or 7.2 percent fewer members than the current level of 1.42 million, according to the Congressional Research Service.

The smaller force would still be capable of taking on terrorists as well as defeating aggression and projecting power in the face of opposition from countries such as China and Iran, according to the Pentagon.