The airport used to be under the control of Zintan brigades which are allied with the eastern commander Field Marshall Haftar.
The brigades attacked
the Libyan parliament in Tripoli in May of 2014 after Haftar began his Operation Dignity to clear Libya of all Islamists who opposed him. However, Islamists grouped together as Libya Dawn
clashed with the Zintan brigades and eventually drove them from the international airport that they controlled, and eventually the city of Tripoli. The brigades still control considerable territory to the west of Tripoli. Wikipedia notes:
On 14 July 2014, the airport was the site of fierce battle as militias from the city of Misrata attempted to take control of the airport. The airport has been closed to flights since the clashes. On 23 August 2014, after 10 days of clashes, Zintan forces, which controlled the airport, withdrew. The Los Angeles Times reported that at least 90% of the airport's facilities, and 20 airplanes, were destroyed in the fighting.
Actually only part of the airport was opened today the old terminal for Very Important Persons (VIP). The terminal escaped the 2014 destruction and has been rehabilitated and revamped and was presented as the new Tripoli airport.
The Salvation government
was formed with the General National Congress (GNC) as its legislature after the elections of June 2014:
The General National Congress (Arabic: المؤتمر الوطني العام) was a body formed by politicians from the blocs that lost the June 2014 elections in Libya. The GNC had appointed an alternative government for Libya, styled the National Salvation Government, which was led by Khalifa al-Ghawi.  The term Libya Dawn Coalition was used to refer to the armed groups and/or the wider political movement supporting the new GNC. The new GNC was one of the major sides in the ongoing Second Libyan Civil War from its formation August 2014 until its dissolution in April 2016.
While Wikipedia speaks of the dissolution of the GNC in April of 2016 this is somewhat misleading. When the UN-brokered Government of National Accord(GNA)came to Tripoli the Salvation government lost most of its power to the GNA. The Libya Herald
speaks of the administration of the Salvation government as vanishing and of Ghwell fleeing to Misrata. Eventually a number of members of the GNC met and accepted the Libya Political Agreement(LPA) and the GNA and then dissolved themselves and then met as the State High Council of the GNA as described in a DJ article.
Ghwell and other members of the GNC rejected this meeting. So some of the leaders of the GNC still considered it as existing and not dissolved.
No one paid any attention until on October 14th last year Al-Ghwell along with others regained control of the Rixos hotel complex that had been the headquarters of the GNA State High Council. However, it had formerly been the headquarters of the GNC and the Salvation government but was seized by militia loyal to the GNA. Within a couple of days many of the Presidential Guards of the GNA defected
to support Ghwell and the coup. Here it is four months later and the coup is still ongoing. On 5th of November, officials from the GNA were not allowed at the opening of a new power station only those from the Salvation Government. Just over a week ago,
the Libyan National Guard(LNG) was formed a group of brigades many from Misrata that appear to be loyal to Ghwell and the coup.
At today's opening, all along the Airport Road security was provided by gun-mounted vehicles of the Libya National Guard or Misrata's Al Marsa brigade. While the Libyan flag flew at the main gate, one visitor told the Libya Herald
that he felt he was in Misrata saying: “The guards, the officials – they were all from Misrata.” The Herald also claimed that many of the guests were those seen protesting against the GNA and its Presidency Council in Martyr's Square.
Mahmoud al-Zaghei, commander of the LNG was there along with many prominent Islamists and members of the GNC as were members of the Justice and Reconstruction Party. After the official opening of the airport by Ghwell, the party went outside to see the first plane land. Apparently, it was a small crop sprayer. The new passenger terminal is supposed to be built by Al-Sarih a local company.
The Libya Observer
also covered opening of the airport. Al-Ghwell told the assembled crowd that the reconstruction work had been carried out in less than a year in record time. He said that the government, presumably the Salvation government, was embarked in reviewing bids for purchasing new planes. One wonders how his unrecognized government is able to get funding to buy planes and carry out reconstruction projects. Al-Ghwell
said: “We will contact international companies to buy security equipment for the airport to secure passengers. We will make the most of the strategic location of Libya and make it a hub for transit trade." The airport is expected to be operational by mid-March. A source said that reconstruction at the passenger terminal had reached 60 percent. The foundation stone for reconstruction was laid back in March 2016. Al-Ghwell also claimed that the Salvation government would introduce a plan to develop air transport to increase national revenue. One wonders how all this can happen without any intervention by the authorities of the Government of National Accord. The opening is actually a day before the February 17th Day of Rage that started the rebellion against Gadaffi.