The chairman of the House Armed Services Committee sent a letter to Defense Secretary Chuck Hagel this week blasting the Air Force for ignoring legislation obligating the service to buy three additional Global Hawk unmanned aerial vehicles.

The chairman, Rep. Buck McKeon (R-Calif.), penned the May 13 letter along with Rep. Jim Moran (D-Va.), a member of the House Appropriations Committee’s defense panel.

The Air Force last year attempted to cancel the Global Hawk block 30 program in its fiscal 2013 budget request, citing high costs and capability gaps. Congress however, blocked that effort and restored the funding earlier this year.

In the letter obtained by Defense Daily, the two congressmen noted that the Air Force has still not contracted manufacturer Northrop Grumman [NOC] to build the planned three aircraft under the block 30 version.

“The Air Force has continued to ignore clear congressional intent and has not obligated these funds,” McKeon and Moran wrote. “The FY2013 bipartisan authorization and appropriation process yielded unambiguous statutory direction about the block 30 program, including explicit direction to complete the acquisition of the remaining three block 30 systems.”

Global Hawk. Photo by Northrop Grumman.

Air Force officials testified earlier this month that they would still prefer to not buy the aircraft, reasserting that the cost of operating them will continue to rise and that they would rather use manned U-2 spy planes.

Air Force Chief of Staff Gen. Mark Welsh said on May 9 that the U-2s in certain respects provide better capability for certain intelligence, reconnaissance and surveillance missions because they can carry more capable sensors.

“The quality assessment from our combatant commanders says they would prefer a U2 product in many mission areas over the Global Hawk,” the general said. “The central ranges are longer on the U2 as well, which is beneficial…Those were the big things that drove our assessment.”

The lawmakers urged Hagel to thwart Air Force efforts to avoid buying the three remaining aircraft.

“We encourage you to deny these efforts and ensure that the Air Force is in compliance with current law,” their letter said.

The president of Northrop Grumman Aerospace Systems, Tom Vice, told a handful of reporters on Wednesday that the company has submitted an “unsolicited” proposal to the Air Force for moving forward with the three aircraft.

The Air Force currently has 16 Global Hawk block 30s and two additional ones are under construction.