An ISIS militant with a MANPAD https://twitter.com/Charles_Lister/status/503679240588365824/photo/1 On Sunday, ISIS fighters captured Syria's Tabqa air base, the last Syrian military outpost in an area that is now dominated by the radical Jihadist organization.

The air base had been the scene of intense fighting between ISIS and the Syrian military for the past week. The Syrian Observatory for Human Rights (SOHR) estimates that at least 346 ISIS militants and 170 Syrian forces were killed in the assault.

Securing the Tabqa air base marks yet another victory for ISIS, one that will allow the group to further solidify its hold over northern and eastern Syria.

Additionally, the base provided the militants with weaponry — including anti-aircraft systems — that could enable them to further advance their regional ambitions.

ISIS fighters managed to loot SA-16 man-portable air defense systems (MANPADS), Sidewinder missiles, and even MiG-21B fighter jets.

It is extremely unlikely that the militants have the manpower or the expertise to make use of the jets or the Sidewinder missiles. But the MANPADS pose dangers of their own.

SA-16 MANPADS are shoulder-mounted homing missiles that are relatively simple to use. A missile fired from an SA-16 can reach an aircraft flying as high as 16,000 feet. This would put low-flying aircraft and helicopters at risk of being targeted by the jihadists, raising additional challenges for carrying out airstrikes against ISIS.

ISIS relies on looted military equipment from Iraqi and Syrian military bases. The group has a sizable arsenal of U.S. military equipment, which it seized after taking control of military bases in the major Iraqi city of Mosul. The weapons then made their way to the fight against the Assad regime and the secular rebels in Syria.

The U.S. has been in the process of carrying out airstrikes against ISIS throughout northern Iraq for the past two weeks. The airstrikes have allowed Kurdish and Iraqi soldiers to make gains against the militants, including the retaking of the critically important Mosul Dam.

The Syrian regime air force is also now engaged in carrying out bombing runs against ISIS militants in areas around the Tabqa air base.

The Tabqa air base was the most recent military outpost that ISIS has wrested away from the Assad regime. The militants had previously captured Syrian Brigade 93 and Division 17 in Raqqa Province, near ISIS's de facto capital in the city of Raqqa.

With the seizure of the air base, ISIS has captured all Syrian military bases in the northern province, effectively placing Raqqa entirely under the group's control.