Space programs, aircraft and ship maintenance, and helicopter upgrades are among $1.8 billion in priority weapons programs that were not funded in the Pentagon's fiscal 2011 budget, the military services told Congress in documents released Monday.

Representative Buck McKeon, top Republican on the House Armed Services Committee, released the services' unfunded priorities lists, which were far more modest than those submitted during the Bush administration.

In the past, lawmakers used the unfunded priorities lists to override the Pentagon's wishes and justify added funding for weapons programs in their home districts or states, including Boeing Co's C-17 transport plane.

Over the past two budget cycles, however, Defense Secretary Robert Gates has discouraged the services from circumventing the official budget process by adding too many items to these lists each year.

McKeon said lawmakers would work with the services to understand why certain decisions were made and whether Congress should support or act to improve upon those actions.

In letters to McKeon, top uniformed leaders of the Navy, Marine Corps and Army said the programs they listed were important, but did not outrank the priority programs that were funded in the fiscal 2011 budget.

The Air Force, by contrast, said the programs it listed were requirements with high military value.

The Navy asked for $532 million to pay for added aircraft and ship maintenance work, saying those accounts were stressed by the increased level of operations in Afghanistan.

The Marine Corps identified $351 million in additional funding for upgrades to its CH-53 and the purchase of a KC-130J tanker built by Lockheed Martin Corp, as well two other airplanes.

The Army identified $358.7 million in war-related funding that it said would help commanders in the field, including needed $51 million for advanced GPS receivers and $55 million for psychological operations. It also listed $133 million that would be used for Patriot anti-aircraft missiles.

The Air Force's list totaled $548 million, and included $337 million for maintenance of various weapons systems, including B-2 bombers, C-5 cargo planes, and KC-135 tankers.

The list also included $55 million for an integrated command and control for space superiority and global intelligence operations, as well as $28.7 million for survey, communication and simulator gear for airfield operations in Iraq, Afghanistan and Haiti.

(Reporting by Andrea Shalal-Esa; Editing by Bernard Orr)