A review of the Benghazi attack on the U.S. Consulate in Libya faults "grossly" inadequate security and leadership failures. The Accountability Review Board released its findings late Tuesday night.

U.S. Ambassador Chris Stevens and three other Americans were killed in the Sept. 11 attack.

Former ambassador Thomas Pickering and Adm. Mike Mullen, former chairman of the Joint Chiefs of Staff, led the review. They studied thousands of documents, cables, videos, and intelligence information and will present their findings Wednesday to the House and Senate Foreign Affairs Committees.

The review blamed woefully inadequate security and over-dependence on Libyan militias for the tragedy.

It stated that "systematic failures and leadership and management deficiencies at senior levels within two bureaus of the State Department resulted in a Special Mission security posture that was inadequate for Benghazi and grossly inadequate to deal with the attack that took place."

The report also noted that State Department officials in Washington denied repeated requests for more security, stopping short of singling out individuals or finding fault with the U.S. military and concluding that there wasn't enough time for a response.

The board also confirmed that despite initial reports by the Obama administration, no protest took place outside the compound before the attack and that it was, in fact, a terrorist attack.

Administration officials blamed protests over an anti-Islam film. U.N. Ambassador Susan Rice made the same claims in appearances on several TV talk shows in the days following the attack.

The backlash from the White House's initial response led her to withdraw her name from consideration for secretary of state.