Updated

The United States has informed the U.N. Security Council that a top suspect in the deadly 2012 assault in Libya was captured because U.S. investigators determined that he planned further attacks against Americans.

In a letter to the council obtained Wednesday by The Associated Press, U.S. Ambassador Samantha Power said the capture of Ahmed Abu Khattala was necessary "to prevent such armed attacks" and was carried out "in accordance with the United States' inherent right of self-defense."

She called Abu Khattala "a senior leader of the Libyan militant group Ansar al-Sharia-Benghazi in Libya."

Power said U.S. investigators determined that Abu Khattala was "a key figure" in the Benghazi attacks that killed four Americans including Ambassador Chris Stevens.

Power said Abu Khattala will be prosecuted in a U.S. federal court.