Meanwhile, the U.S. House Oversight Committee held a hearing Wednesday on the administration's handling of the attack in Benghazi, Libya, that killed U.S. Ambassador Christopher Stevens and three other Americans.

Under Secretary of State for Management Patrick Kennedy rebutted criticism by Republicans of an alleged lack of preparedness ahead of the consulate attack and a shifting response by the Obama administration following the assault.

"We regularly assess risk and resource allocation, a process involving the considered judgments of experienced professionals on the ground and in Washington, using the best available information," Kennedy told the Republican-controlled committee.

The assault on the U.S. compound was "an unprecedented attack by dozens of heavily armed men," Kennedy said.