Who is Mustafa Al-Islam? Benghazi Attack Suspect Captured in Libya to Face Trial in U.S.

Five years after the most significant attack on a U.S. diplomatic facility since 1998, United States forces have captured another of the alleged perpetrators of the 2012 Benghazi attacks.

President Donald Trump announced on Monday that Mustafa Al-Imam was captured "on my orders" in Libya on Sunday. The president said that Imam "will face justice in the United States" for his alleged role in the attack, which left four Americans dead.

The attack on the U.S. mission in Benghazi sparked political soul-searching in the United States and became a campaign flashpoint during the 2016 presidential election, with Trump frequently citing the incident—which occurred while Democratic candidate Hillary Clinton was secretary of state—as evidence of his opponent's unfitness for office.

Here's what we know about the latest development.

What happened in the Benghazi attacks?

On the evening of September 11, 2012, a group of heavily armed militants attacked the U.S. diplomatic compound in Benghazi. The attackers set fire to the main building in the compound, where Ambassador Christopher Stevens and State Department official Sean Smith had taken refuge. Both men died in the attack.

Hours later, gunmen launched mortars against a CIA annex located around one mile from the diplomatic compound. Two CIA contractors—Tyrone Woods and Glen Doherty—died in the attack.

The U.S. Consulate in Benghazi is seen in flames after an attack by armed militants in Benghazi, Libya, on September 11, 2012. Four U.S. nationals were killed in the attack and a linked attack on a nearby CIA annex. Esam Al-Fetori /Reuters

U.S. officials eventually blamed the attack on members of Ansar Al-Sharia—which was designated a foreign terrorist organization in 2014 by the State Department—after initially saying that it resulted from a spontaneous protest by people outraged by a video, Innocence of Muslims, that sparked protests around the Islamic world.

Who is Mustafa al-Imam?

The Justice Department considers Imam, a Libyan national of around 46 years old, to be one of the key plotters of the 2012 attacks, according to statement. He faces three charges—killing a person in the course of an attack on a federal facility; providing or attempting to provide material support to terrorists; and discharging or brandishing a firearm during a violent crime—according to a recently unsealed criminal complaint originally filed in May 2015.

A team of commandos from the Navy SEAL Team Six and the FBI's Hostage Rescue Team captured Imam in a surprise raid in the Libyan city of Misrata on Sunday, the New York Times reported. Officials told the Times that Imam had been living in Tripoli but recently traveled to the coastal city of Misrata. After his apprehension, he was transferred to a U.S. warship and will be brought to the United States to face trial.

Who else was involved?

The U.S. captured the prime suspect in the attacks, Ahmed Abu Khattala, in a raid in Benghazi in June 2014. Officials have long characterized Khattala as the ringleader of the attacks and as a senior figure in Ansar al-Sharia. But in the wake of the attacks, Khattala did not flee Benghazi and gave multiple interviews to U.S. news organizations, denying any role in the attacks.

Read more: The group blamed for the Benghazi U.S. mission attack is disbanding—here's why

Khatallah faces 17 charges, including the murder of an internationally protected person and three counts of murder of an officer and employee of the United States. Some of the crimes are punishable by death, though the Justice Department said it would not be seeking the death penalty. Khatallah pled not guilty to the charges when his trial opened earlier in October.

People stand near a burnt car at the U.S. consulate in Benghazi, Libya, on September 12, 2012. Esam Al-Fetori/Reuters

What is the U.S. still doing in Libya?

In his Monday statement, President Trump said that the United States would "continue to support our Libyan partners to ensure that ISIS [Islamic State militant group] and other terrorist groups do not use Libya as a safe haven for attacks against United States citizens or interests, Libyans and others." Trump also said that the North African country's long-term stability and security depended on "its ability to form a unified government and military" and urged Libyans to support United Nations-led efforts to form a unified government.

Since the ousting of Muammar El-Qaddafi in 2011, Libya has descended into civil war, riven by conflict and divided among several competing administrations. The United States has largely restricted its involvement to targeting ISIS hideouts in the country. Between August and December 2016, the U.S. military launched almost 500 airstrikes to drive ISIS out of their stronghold in in the city of Sirte, around halfway between Tripoli and Benghazi. In September, Washington launched its first strikes in Libya since January, targeting a ISIS training camp around 150 miles southeast of Sirte.

Why was Benghazi such a big issue in the election?

The Benghazi attacks loomed large over Clinton's campaign. Critics accused Obama administration officials of covering up the attack's apparently premeditated nature and State Department officials for rejecting requests for additional security at the Benghazi compound prior to the attacks.

Then-U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee about the September 11, 2012 attacks against the U.S. mission in Benghazi, Libya, on Capitol Hill in Washington, D.C., January 23, 2013. Alex Wong/Getty

Clinton faced an 11-hour grilling by the House of Representatives Select Committee in October 2015 on the topic of the attacks. The hearing frequently focused on Clinton's use of a private email server while in office as secretary of state, another issue that the Trump campaign gained much political capital from during the election.