After having been beleaguered for close to three years, Abu ad-Duhor airbase has finally been captured by rebels, mainly of the al-Nusra Front, on the 9th of September 2015. Battling the longest siege of the Syrian Civil War, the fall of the airbase ultimately proved to be inevitable. Abu ad-Duhor is now the eight airbase to have fallen to the numerous factions opposing the regime, and leaves the Syrian Arab Air Force (SyAAF) with fifteen operational airbase to conduct sorties from.
Although often rumoured to still be housing operational aircraft and helicopters flying sorties over Syria's Idlib Governorate, the last operational airframes left Abu ad-Duhor months prior to its fall. Fully aware that the fall of the airbase was imminent, and with tactical insight normally not seen within the ranks of the Syrian military's high command, the decision was made to evacuate the remaining few operational MiG-23MFs, MiG-21MFs and MiG-23bis's to Hama airbase. Although an impressive sight, most of the more eighteen derelict airframes seen on Google Earth as well as in images and videos were abandoned ten to fifteen years ago. The fall of Abu ad-Duhor will thus have little to no effect on the SyAAF's ability to exercise control over the Syrian skies.
As Abu ad-Duhor was completely cut off from the rest of regime-held territory, the task of resupplying the airbase was in the hands of the SyAAF, which mainly used An-26s and Mi-8/17s to bring in anything from food to weapons, an ever more hazardous taskover time as rebels continued to move closer to the perimeter of the airbase. Several helicopters were shot down, destroyed or damaged throughout the years, along with the loss of two MiG-21s and one An-26.
The storming of Abu ad-Duhor airbase coincided with the huge freak sandstorm blazing through the Middle East, which prevented the SyAAF from flying sorties in support of the defenders. Even still, it was the constant bombardment, the attrition caused by the nearly three years of besiegement and the numerical superiority of the rebels that ultimately led to the capture of the airbase. While the majority of the defenders were captured or killed, a small part fled towards regime-held territory. The commander of Abu ad-Duhor, Ihsan al-Zuhouri, was reportedly killed in action.
Abu ad-Duhor was home to 678 Squadron flying the MiG-23MS, MiG-23MF and MiG-23UB, and to an unknown Squadron flying the MiG-21MF, MiG-21bis and MiG-21UM. Originally received in 1973 and undoubtedly one of the worst military aircraft in history, the MiG-23MS was at the end of its (already stretched) lifespan at the turn of the century. 678 Squadron slowly winded down operations throughout the early 2000s and the MiG-23MS was formally decommissioned around 2005, leaving just a couple of MiG-23MFs, MiG-23UBs and the MiG-21s as the only operational assets at the airbase. One of the MiG-23MS's '1614' in better times can be seen below.
The first serious attempt to capture Abu ad-Duhor already occurred on the 30th of April 2013, when fighters of the Free Syrian Army managed to penetrate the perimeter of the airbase. The defenders succeeded in repelling the Free Syrian Army however, ending the first attempt that infiltrated the airbase. The defensive lines were reinforced immediately thereafter, and fenced off every assault in the following months. The fighters of the Free Syrian Army struck the airbase with an 9M131 (9K115-2 Metis-M) ATGM on the 7th of March 2012, damaging one of the already inoperational MiG-23MS's, which was later encountered again when Free Syrian Army fighters stormed the base. Nearly five-kilometers in length, the perimeter of Abu ad-Duhor was almost impossible to defend without any high structures overlooking the flat terrain surrounding the airbase. Much of of the villages and farms around the airbase were already leveled to deny the rebels any cover. The thirteen Hardened Aircraft Shelters (HAS), most of which now empty, were turned into strongholds, holding groups of defenders with various light and heavy weaponry. Heavy machine-guns and ATGMs were installed on top of the HAS's, providing the defenders with a clear field of fire. The presence of these HAS's played a significant role in the airbase's nearly three year long survival.
The defenders could count on the support of several tanks and armoured fighting vehicles attached to the several checkpoints along the perimeter, which could also be deployed as a quick-reaction force. Indeed, although besieged, the defenders of Abu ad-Duhor left the airbase several times to conduct raids against enemy positions, mostly to neutralise the rebels' artillery. In their attacks on the airbase, al-Nusra Front (including many Tribesmen from rural Deir ez-Zor who fled from the Islamic State) lost several tanks to the defenders, some of which were then turned against their previous owners.
Although the airbase won't provide the rebels with large amounts of weaponry and ammunition, the capture does represent a serious boost of morale for the rebels. The sight of a captured MiG aircraft, operational or not, remains a symbol of victory. In terms of (useful) ghaneema (spoils of war), Abu ad-Duhor provided the rebels with several tanks, armoured fighting vehicles, one ZSU-23, several 130mm M-46 field-guns, anti-aircraft guns, trucks and small arms and ammunition. As taking images of aircraft and helicopters is more popular than taking images of vehicles, and as it remains unknown how much of the vehicles and equipment was evacuated by the fleeing defenders, real numbers on the captured equipment are hard to come by. Ten ATGMs captured in one of the HAS's are actually empty canisters, comprising three 9M111 Fagots, five 9M113 Konkurs, and two 9M131 Metis-Ms.
As could be expected, much of the fleet of vehicles and equipment once used for operating jet aircraft was also captured. The damage and rust on these vehicles show that operating fighter aircraft ultimately became nigh impossible here, and was aborted with little care.
As can be seen below, about a dozen multiple ejector racks (MERs) were captured as well.
Semi-active radar homing R-23R and infrared guided R-23T air-to-air missiles can be seen below. Once arming Abu ad-Duhor's MiG-23MFs, most were still wrapped in their protective cover they arrived in when they were delivered roughly 35 years ago.
Several of the SyAAF's indigenously designed chaff/flare launchers along with boxes holding even more air-to-air missiles and rocket pods. Numerous drop tanks for the MiG-21s and MiG-23s were also found, most of them apparently used as target practise.
678 Squadron provides the bulk of the airframes, with eleven MiG-23MS', two MiG-23UBs and one MiG-23MF found in the North-Western part of the airbase. It is here where the majority of the MiG-23s were dumped since their decommissioning in the 2000s.
Arguably the most worn airframe of all, with even its camouflage pattern completely washed out, can be seen below. As evident by the symbol left of its nose, this MiG-23MS was once overhauled by 'The Factory', the SyAAF's overhaul and maintenance facility at Neyrab airbase/Aleppo IAP.
MiG-23MF '3677' was the only aircraft of this type that was not evacuated to Hama months ago. The remaining technicians were likely unable to repair its tail after it was hit by an ATGM, and decided to leave it as it would be largely useless to its captors anyway. This was the third airframe to have been hit by an ATGM, with every missile striking the tail of the aircraft. Of course, as both other aircraft were already inoperational when they were struck, it is also the only case where the ATGM strike achieved its goal.
A total of four MiG-21s were captured at Abu ad-Duhor (excluding the MiG-21F-13 gateguard), comprising two MiG-21MFs, one MiG-21bis and one MiG-21UM. All were inoperational for at least one and a half year, and thus unable to evacuate to Hama as well.
The single MiG-21bis found in the other part of the HAS. All aircraft had their guns removed prior to the fall of the airbase, presumably cannibalised and flown to Hama for use in the few remaining operational MiG-21MFs and MiG-21bis'. 
Two Mi-8s were also encountered, one of which, Mi-8 '1282' was fitted with a minelaying system and probably saw action near Abu ad-Duhor before ending up on the local scrapyard after getting damaged in combat. In the back, the same MiG-23MS described earlier, clearly showing its tail end scattered apart in the grass.
The other Mi-8, victim of an ATGM attack or mortar fire. The ensuing fire that consumed the airframe made sure it would never fly again.
