A House panel is warning that large Pentagon budget cuts, which could come if lawmakers fail to reach a deficit-cutting plan, would significantly impact funding for maneuver battalions, fighter wings, shipbuilding, long-range strike, and airlift.

Staff members on the Republican-controlled House Armed Services Committee (HASC) describe in a new eight-page memo what they believe would happen to the Defense Department if a failure in congressional budget-cutting negotiations this year triggers nearly $600 billion in additional defense reductions, on top of those already mandated in the new deficit-cutting law approved in August.

“Cuts to investment accounts would significantly reduce operational capability, increase risk, and limit DoD’s ability to support the National Military Strategy,” they write. “Impacts would be felt in Army maneuver battalions, fighter wings, shipbuilding, long-range strike, and air lift.”

The memo to HASC Chairman Howard “Buck” McKeon (R-Calif.) says the “worst case” Pentagon budget scenarios described also would come if the Pentagon’s FY ’13 budget is 10 percent less than in FY ’11, for which the White House has directed federal agencies to prepare.

The worst-case cuts would hit the military in multiple areas–including nuclear deterrence, missile defense, Marine Corps missions, Navy shipbuilding, technological innovation, and small-business contracting, the HASC staff write.

The memo singles out Pentagon modernization programs the staffers see as being at risk if the largest-possible cuts are made. Those include the Army’s Ground Combat Vehicle, tactical-wheeled vehicles consumed in Iraq and Afghanistan, and AH-64 Apache and OH-58 Kiowa helicopters.

For the Navy, the carrier-variant of the F-35 Joint Strike Fighter could be cut, up to 30 additional ships could come out of the inventory, shipbuilding capabilities such as ballistic-missile defense could be significantly degraded, aircraft-carrier construction could be extended, and the procurement of the Ohio-class ballistic-missile submarine program could be extended with fewer ships, the memo says.

The HASC staff warn the Air Force’s next-generation bomber and aerial-refueling tanker aircraft would be at risk if the largest cuts are made, and the air service could be forced to reduce its buy of the convention-take-off-and-landing variant of the F-35.

They predict the Marine Corps’ short-takeoff-and-vertical-landing F-35 would likely be outright eliminated, while six amphibious ships could be lost, the nascent Amphibious Assault Vehicle program could be indefinitely shelved, the new Marine Personnel Carrier effort could be at risk, and the production of V-22 tilt-rotor aircraft could be restricted.

The memo has a complete section titled “United States Marine Corps at Risk,” which warns the worst-case defense cuts would leave the country without the capability to fulfill combatant commander requirements to conduct an opposed amphibious landing with two Marine Expeditionary Brigades. It predicts a curtailment of Marine Corps non-combatant evacuations and humanitarian and disaster assistance missions, and says a significant re-evaluation of the Marine Corps’ mission would be required.

The staffers enumerate impacts the biggest-possible cuts could have on the Marine Corps, the only service singled out in the memo, including a potential indefinite postponement of equipment reset.

“These impacts reduce the ability of the service to be ‘the most ready when the nation is least ready’ and call into question the role of the service,” they write.

In summary, the staffers warn McKeon, and outspoken defender of the Pentagon budget, that the worst-case budget reductions would “significantly delay force modernization for a force structure of aging fighter aircraft and Army and Marine Corps ground vehicles that have experienced extended years of high operational tempo, by delaying fielding schedules–with associated increased operational risk and maintenance costs.”

They add the cuts would: “Severely curtail research and development of advanced aircraft; ground vehicles; intelligence and electronic equipment for the brigade, air wing, and the individual soldier and Marine. Reduce individual soldier and Marine operational capability, individual mobility, and situational awareness by curtailing development of advanced personal communications equipment and light-weight body armor.”

While they do not expect special-operations forces to be impacted by the worst-case defense cuts, the HASC staffers warn “their reliance on conventional forces for mobility and other assets may increase.”

“As a result, the ability of the United States soldier, sailor, airman, or Marine to maintain a technological advantage on the battlefield would be in jeopardy,” the memo says.

“National operational capability to meet traditional nation state 5th generation aviation, as well as asymmetric threats, would be limited,” it adds. “The military would witness increasing specialization at the expense of a general purpose force trained to respond to a full spectrum of missions.”

If the new congressional Joint Select Committee on Deficit Reduction and Congress cannot agree on a plan to cut up to $1.5 trillion in longterm federal spending this year, an automatic sequester will slash roughly $600 billion in defense spending over a decade. That’s on top of what the Pentagon says is $450 billion in multi-year defense reductions mandated in the first wave of spending cuts mandated in the Budget Control Act of 2011 that President Barack Obama signed Aug. 2.

The HASC staffers also note in their memo, dated Sept. 22, that Defense Secretary Leon Panetta warned cuts brought about by the sequestration process would kill at least 1 million jobs in the Pentagon and defense industry. Those impacts could be significant in Virginia, Texas, and California, they note.

“Anticipate additional contraction/consolidation within the defense industry, reducing competition, and eliminating entire sectors of the industrial base,” the memo says, further warning of “shuttering of U.S. shipyards” and the “inability to rapidly reconstitute critical skills in response to emergent threats.”