WASHINGTON — Defense Secretary Chuck Hagel warned on Wednesday that if across-the-board budget cuts were not lifted, the United States would have to reduce its global security objectives by trading away the size of its armed forces or its edge in technology as the Pentagon seeks to remain solvent.
In a dire assessment of the financial challenges facing the military, Mr. Hagel said the political stalemate between the White House and Congress over a comprehensive deal for taxes and spending has required the Defense Department to plan for a range of cuts, since a deal to lift the across-the-board budget cuts known as the sequester remains elusive.
Under the largest cuts the Pentagon is considering, Mr. Hagel described a trade-off: The military, he said, could maintain its size — as measured in the number of Army brigades, Navy warships, Air Force fighter squadrons and Marine expeditionary units — but not buy the most advanced new weapons. Or, he said, the Pentagon could shrink the force and put money into the next generation of weaponry.
A decision to trade numbers for capability would involve a large drop in the size of the active-duty Army, which could shrink to between 380,000 and 450,000 troops. The Marine Corps would drop to between 150,000 and 175,000 personnel. (Under current budget orders, the Army already is set to fall over five years to 490,000 from a peak of 570,000, and the Marines are to drop to 182,000 from 202,000. The ground forces still would be slightly larger than they were before the attacks of Sept. 11, 2001, the beginning of a decade-long military buildup
The largest Pentagon cuts would also require a concurrent reduction in aircraft carrier strike groups to 8 or 9 from 11. In addition, some number of Air Force squadrons could be retired.
“This strategic choice would result in a force that would be technologically dominant but would be much smaller and able to go fewer places and do fewer things, especially if crises occurred at the same time in different regions of the world,” Mr. Hagel said at a Pentagon news conference.
The other option — to maintain a sizable military to assure an overseas presence and project global power — would require the cancellation or curtailment of weapons programs, while slowing the development of cyberwarfare tools and reducing the number of Special Operations forces, Mr. Hagel said. Dollar for dollar, cybertools and Special Operations forces are considered among the most cost-effective in the Pentagon budget.
This decision would result in what Mr. Hagel termed “a decade-long modernization holiday.”
Regardless of whether the sequester cuts are lifted or reduced, Mr. Hagel indicated that the Army and Air Force were still likely to shrink. He said the assessment indicated that the military could still execute “the priority missions” with an active-duty Army of between 420,000 and 450,000 troops and a reserve component between 490,000 and 530,000. The current plan for the reserves is a force of 555,000. Mr. Hagel said the end of the Iraq war and the withdrawal from Afghanistan required the fresh look at Army force levels.
The Air Force could reduce its tactical air squadrons by up to five and cut the size of its C-130 cargo fleet “with minimal risk,” Mr. Hagel said.
He stressed that no final decisions had been made.
The assessment, called the “Strategic Choices and Management Review,” was conducted over four months and looked at several spending plans. The full sequester would cut an additional $52 billion next year, with $500 billion over a decade. A middle plan would reduce military spending by about $250 billion over a decade. The plan with the smallest Pentagon reductions was based on a White House budget proposal for cuts of $150 billion over the next 10 years.
But even without these cuts, the Pentagon must reduce its spending by $487 billion over a decade under an agreement with the White House.
“The review showed that the ‘in-between’ budget scenario we evaluated would ‘bend’ our defense strategy in important ways, and sequester-level cuts would ‘break’ some parts of the strategy no matter how the cuts were made,” Mr. Hagel said. “Under sequester-level cuts, our military options and flexibility will be severely constrained.”
The defense secretary briefed President Obama on the emerging assessment of how a range of budget cuts would be felt across the fighting force, including the challenge to Mr. Obama’s “Defense Strategic Guidance” — which laid out the current military strategy — signed in January 2012.
“No decisions have been taken that would break the strategy at this juncture,” said one White House official, speaking on condition of anonymity to discuss sensitive military planning under the sequester. “This is bounded by the work we still are doing to secure a budget deal. Our judgment is, this is not the way to manage defense cuts. If we want to reduce defense spending, which we do, we want to do it in a way that is strategic. These are not strategic reductions.”
Mr. Hagel also warned of serious reductions in some parts of the military compensation package, especially health benefits to retirees. He also said housing subsidies to military personnel could be trimmed and pay raises to service members and civilians could be limited.
A version of this article appeared in print on August 1, 2013, on page A11 of the New York edition with the headline: Hagel Gives Dire Assessment of Choices He Expects Cuts to Force on the Pentagon.