The suspected ringleader of the deadly 2012 assault on an American compound in Benghazi was planning new attacks on Americans, the United States says, defending the raid that captured the Libyan militant.
US commandos seized Ahmed Abu Khatallah near the Libyan city of Benghazi on Sunday, drawing condemnation from Tripoli, which considers the stealth raid an infringement of its sovereignty.
But in a letter addressed to the president of the UN Security Council for June, Russian Ambassador Vitaly Churkin, US envoy Samantha Power evoked "the United States' inherent right of self-defense."
"Following a painstaking investigation, the US government ascertained that Ahmed Abu Khatallah was a key figure" in the September 11, 2012 Benghazi assault, her letter, dated Tuesday, read.
"The investigation also determined that he continued to plan further armed attacks against US persons," it added.
"The measures we have taken to capture Abu Khatallah in Libya were therefore necessary to prevent such armed attacks and were taken in accordance with the United States' inherent right of self-defense," Powers wrote.
She explained she sent the letter as required by article 51 of the UN charter.
The article requires member states who take measures to defend against an attack to immediately inform the Security Council, which acts as a guarantor of peace and international security.