(CNN) — Defense Secretary Leon Panetta will answer questions Thursday about the attack on the U.S. Consulate in Libya that left four Americans dead.
In the months since the September 11 tragedy in Benghazi, Washington has been on fire with debate about how much the State Department knew about threats in the region and whether the administration attempted to mislead the public about the nature of the attack.
Arizona Sen. John McCain and other Republicans have said the administration's initial explanation about the attack wasn't forthright.
Panetta and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey are expected to tell the Senate Armed Services Committee what they understand happened in Benghazi and how a similar attack might be prevented in the future.
A scathing independent report released in December lambasted the State Department, saying "systemic failures and leadership and management deficiencies" led to inadequate security at the consulate.
Panetta's appearance comes a few weeks after passionate testimony from then-Secretary of State Hillary Clinton, who told lawmakers that the State Department was moving fast to beef up security at U.S. posts worldwide.
One of the most memorable moments in Clinton's testimony was when she teared up recalling meeting the caskets of U.S. Ambassador to Libya Chris Stevens and Tyrone Woods and Glen Doherty, both former Navy SEAL commandos who had been working as diplomatic security officers. The fourth American killed was Sean Smith, an information management officer.
Thursday's hearing occurs as President Barack Obama attempts to reorganize his national security team. Some Republicans have been critical of former Sen. Chuck Hagel's nomination to replace Panetta.
But CNN has learned there are now at least five Republican senators who would oppose a filibuster of Hagel, all but ensuring the embattled nominee will be confirmed in the coming days.
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