By Mike Mount
(CNN) - A day after CNN's Security Clearance reported that the diplomatic office in Benghazi, Libya, had less than standard security before an attack there killed four Americans, two U.S. senators have demanded details of the threats and security concerns ahead of the attack.
U.S. Sens. Johnny Isakson, R-Georgia, and Bob Corker, R-Tennessee, both members of the Senate Foreign Relations Committee, penned a letter to Secretary of State Hillary Clinton on Tuesday requesting that the she provide the committee with "all communication relevant to the security situation in Benghazi between the U.S. mission and the State Department leading up to the attacks, including any cables sent from Ambassador Stevens," according to a news release from the offices of the two senators.
Ambassador Christopher Stevens was one of the four Americans killed in the September 11 attack on the U.S. mission.
"We are extremely concerned about conflicting reports over events leading up to the attacks. Specifically, we are concerned over the apparent lack of security preparation made despite a demonstrable increase in risks to U.S. officials and facilities in Benghazi in the period leading up to the attacks," the letter to Clinton says.
In the letter, the senators cited a Monday CNN report about a waiver allowing the diplomatic office to have a lower security level as well as earlier reporting by CNN that Stevens was concerned about the deteriorating security situation in Benghazi. That reporting came from a diary found by CNN in the burned-out mission that was confirmed to belong to Stevens.
The letter to Clinton is the latest request by members of Congress asking how the attack happened and how it was able to become so violent.
In addition to the letter from Isakson and Corker, Sen. Lindsey Graham, R-South Carolina, has called for an investigation. And Sens. Barbara Mikulski, D-Maryland, Dan Coats, R-Indiana, Bill Nelson, D-Florida, and Roy Blunt, R-Missouri, have sent a letter to Clinton questioning host-nation perimeter security at State Department facilities overseas.