A US District Court judge sentenced a Libyan national to 19 years and six months in prison over terrorism charges.
Mustafa al-Imam, 47, was captured by US special forces in Libya and brought to the US for trial for his role in the 2012 attack on the US mission in Benghazi.
US ambassador Chris Stevens and three other Americans died in the September 11 attack in 2012.
"Each sacrificed his life promoting American ideals," Secretary of State Mike Pompeo said in a statement, adding that Imam's sentencing "sends a strong message to those who would attempt to commit such a heinous crime."
For her part, US attorney Jessie Liu said in a statement reported by AFP: "Imam played an important role in the terrorist attack that destroyed the US mission and the CIA annex in Benghazi."
"Today's sentencing is a reminder that the safety of Americans -- whether at home or abroad, civilian or otherwise -- will always be our top priority," she added.
According to prosecutors, Imam was in contact during the attack on the US mission with Ahmed Abu Khattala, another Libyan national who was captured by US troops in 2014 and also brought to the US.
Khattala was sentenced to 22 years in prison in June 2018 over the Benghazi attack.
