Initial probing of the Tuesday night assault on the U.S. Consulate in Libya that resulted in the death of Ambassador Chris Stevens and three other officials suggests the attackers had coordinated with each other prior to taking action, government officials said.
Sources said there were signs the extremist group Ansar al-Sharia had a role in orchestrating the assault in Benghazi, Reuters reported. Reports also indicate al-Qaida's North Africa branch, al-Qaida in the Islamic Maghreb, could also have been involved, officials said.
"It bears the hallmarks of an organized attack" and looks to have been strategized ahead of time, an anonymous U.S. official said.
Stevens, State Department information systems specialist Sean Smith and two still-unidentified U.S. security officers were killed when armed assailants invaded the diplomatic outpost and a nearby U.S. refuge in Benghazi.
President Obama said on Wednesday the killers would be brought "to justice."
The U.S. Navy is deploying two destroyers to waters near Libya in order to expand the options for responding to the evolving security situation there, a different official informed Reuters on Wednesday.
Following the 2011 fall of the long-ruling Muammar Qadhafi dictatorship, a number of Libyan government weapon caches were plundered, allowing local extremist groups to acquire more sophisticated arms.
The London-based Quilliam Foundation on Tuesday posited the Benghazi attack was revenge for a June U.S. unmanned aircraft strike that left al-Qaida's No.2 official, who was Libyan, dead.
Just one day prior to assault on the consulate, al-Qaida chief Ayman al-Zawahiri released a video to extremist websites in which he verified the death of Abu Yahya al-Libi and called for revenge strikes.
Four people were taken into custody on Thursday in connection with the assault on the consulate, Reuters reported.
Libyan authorities have made four arrests in the investigation into the attack on the U.S. consulate in Benghazi in which the U.S. ambassador and three embassy staff were killed, Reuters reported on Thursday.
"Four men are in custody and we are interrogating them because they are suspected of helping instigate the events at the U.S. consulate," Libyan Deputy Interior Minister Wanis Sharif said without providing additional specifics.