General Khalifa Haftar has emerged as a key player in Libya's civil war, with his self-styled Libyan National Army seizing the country's main oil fields and export terminals for the rival government backing him in the east.    

A former officer in Libya's army, Haftar participated in the 1969 coup that ousted King Idris and brought Colonel Muammar Gadhafi to power.

Read more: Libya: The road from revolution to civil war 

He had a falling out with Gadhafi following the Libya-Chad war, which Libya lost in 1987. Haftar, who had commanded Libyan forces during the war, was captured by Chad and subsequently transferred around 1990 to the United States, where he was part of the CIA-backed anti-Gadhafi opposition. From the northern Virginia suburbs outside Washington, he spent the next two decades plotting to overthrow and assassinate Gadhafi.

Haftar returned to Libya in 2011 during the NATO-backed uprising that ousted and killed Gadhafi, and rose to become one of the top military commanders leading rebels.

Descent into civil war

In February 2014, Haftar announced on television that the now-defunct General National Council (GNC) had been disbanded and called on Libyans to rise up against the body to pave the way for elections. 

The crisis erupted as the 18-month transitional mandate of the GNC was controversially extended, although the mandate was still in effect at the time. The government labeled Haftar's move an attempted "coup d'etat."

In May 2014, Haftar and allies from the Zintani militias launched Operation Dignity against Islamist militias in the eastern city of Benghazi. 

In June, contested parliamentary elections won by anti-Islamist groups led to the formation of two rival administrations: one in the western capital Tripoli and another in the east.

Fighting in Tripoli between Misrata-based militias and Islamist factions on one side and forces loyal to Haftar on the other ultimately led the newly elected House of Representatives to move the eastern city of Tobruk. In March 2015, the House of Representatives in the east appointed Hafter commander of the Libyan National Army.

Although proclaimed to be the Libyan National Army, the force is comprised of military units, ex-police officers, tribal militias and locally-based armed groups.

Haftar has presented himself as a seasoned nationalist commander capable of taking on an array Islamist militias, some of which back the Tripoli-based government. But his past associations with Gadhafi's regime and the United States has made him an unpopular figure for some in Libya. 

Since 2014, Haftar's forces have wrested control of Libya's oil crescent from mostly government-aligned militias and Islamist groups in the east where oil fields and export terminals are located.

Elusive power-sharing deal

In 2015, the UN-brokered a power-sharing deal established a body known as the Presidency Council, led by Fayez Serraj. The internationally recognized government was installed in Tripoli in early 2016 but it has since struggled to exert control over the country and numerous militias around Tripoli.

The Presidency Council and the government it oversees, the interim Government of National Accord, were supposed to bridge political differences between the rival administrations in the east and west.

However, the House of Representatives, which remained the internationally recognized legitimate parliament, never endorsed the Government of National Accord as envision by the UN-backed deal.

UN, French, Italian and Gulf Arab states have since sought to mediate a political deal between Haftar and Serraj to end the civil war. The UN has also sought to hold a conference to develop a roadmap for delayed parliamentary and presidential elections aimed at uniting the country.

Haftar reportedly seeks to become the head of Libya's army under any national reconciliation deal, with the Libyan National Army to become the country's armed forces. But with his forces now at the gates of Tripoli, Haftar may calculate that military force can be used to grab power or be leveraged to extract demands during negotiations.