The Pentagon broke the law when it swapped Army Sgt. Bowe Bergdahl, a prisoner in Afghanistan for five years, for five Taliban leaders, congressional investigators said Thursday.

The nonpartisan Government Accountability Office said the U.S. Defence Department failed to notify the relevant congressional committees at least 30 days in advance of the exchange — a clear violation of the law — and used $988,400 of a wartime account to make the transfer. The GAO also said the Pentagon’s use of funds that hadn’t been expressly appropriated violated the Anti-deficiency Act.

“In our view, the meaning of the (law) is clear and unambiguous,” the GAO wrote to nine Republican senators, including Minority Leader Mitch McConnell and various committees. “Section 8111 prohibits the use of ‘funds appropriated or otherwise made available’ in the Department of Defence Appropriations Act, 2014, to transfer any individual detained at Guantanamo Bay to the custody or control of a foreign entity’ except in accordance” with the law.

The GAO said the relevant committees received phone calls from May 31 — the day of the transfer — to June 1, with written notification coming on June 2.

Five senior Taliban were released from detention at the U.S. prison at Guantanamo in exchange for Bergdahl, who had disappeared from his post in Paktika province in eastern Afghanistan on June 30, 2009. The five Taliban are to remain in Qatar for a year.

Lawmakers, especially Republicans, were furious with President Barack Obama and members of the administration for failing to notify them about the swap. Some in Congress have said Bergdahl was a deserter and the United States gave up too much for his freedom. Several lawmakers have cited intelligence suggesting the high-level Taliban officials could return to the Afghanistan battlefield.

The administration has defended the swap and its decision to keep Congress in the dark, saying concern about Bergdahl’s health and safety required speedy action.

The Joint Chiefs of Staff has unanimously supported the exchange, insisting that the United States has a sacred commitment to men and women who serve that it will never leave anyone behind on the battlefield. Army Gen. Martin Dempsey, the chairman of the Joint Chiefs, said the swap in May was “likely our last, best opportunity” to free Bergdahl.

Bergdahl is doing administrative duties at Fort Sam Houston in Texas while an investigation into how he was captured by the Taliban is conducted.

Last month, a bitterly divided House Armed Services Committee voted to condemn Obama for the swap. The Republican-led panel backed a nonbinding resolution that disapproves of the exchange and faults Obama for failing to notify Congress 30 days in advance of the swap, as required by law.

The bipartisan resolution raised national security concerns about the transfer of the five Taliban, who had been held at the prison at Guantanamo Bay, Cuba, for more than a decade, and the “repercussions of negotiating with terrorists.” The measure also expresses relief that Bergdahl has returned safely to the United States.

The full House is expected to consider the measure in the fall, just a few weeks before the midterm elections.

(AP)