The ISA VTOL is a type of aircraft used in Killzone: Liberation by the ISA as their primary troop transport. It is used several times including transporting Jan Templar to the front trenches and evacuating three VIPs.
There are two versions: the first, as seen in the picture, only has one nose-mounted machine gun. This version is most likely a troop transport. The second type is equiped with several missiles on each side and is used as a gunship instead of a troop transport.