Attacker

An Attacker is a Harvester interceptor-type air/spacecraft. Attackers can be deployed by City destroyers, as well as Colony ships and the Harvester Mothership, even though the latter doesn't seem to be equipped for rapid dispatch.

Performance characteristics
Attackers, also officially known as "Agile Fighters", are extraordinarily technologically advanced feats of alien engineering when compared to humanity's technological achievements. Though their method of propulsion was never elaborated on, it is strongly evident that these attack aircraft have transcended the need for traditional liquid or solid-fuel combustion engines at least while hovering in place, given their lack of the incredible heat and exhaust output necessary to support something its apparent size and mass, such as from a jet engine.

Despite not having wings or maneuvering flaps for stability, Agile Fighters are capable of stable atmospheric flight even at speeds reaching or exceeding the sound barrier while still maintaining an incredible degree of maneuverability and have been demonstrated to have fantastic acceleration power, going from a completely stationary hover to presumably several hundred miles per hour in just a few seconds. It should be noted that all of these handling characteristics have been observed from a badly damaged crash specimen recovered and then repaired, that is presumably the craft from the Roswell New Mexico Incident of 1947; it is probable that a mechanically undamaged and fully stocked Agile Fighter may exhibit even better handling characteristics.

Alien Attack craft are capable of trans-atmospheric flight, allowing a single autonomous unit to leave planets like Earth's atmosphere without needing to be transported aboard a large carrier craft; accordingly, they are equipped with cabin-pressurization, inertial dampening, and life-support systems installed that are sophisticated enough to allow two pilots to sit comfortably inside the craft (and to a lesser extent, survive crash/impact forces) without requiring the need of sealed and pressurized space or G-suits, despite the Agile Fighter's ability to pull incredible-G turns that stress normal air-frames and pilots often to the breaking point. It is probable that a single autonomous Agile Fighter has capability to successfully complete re-entry into a planet's atmosphere at least as dense as Earth's, but as the two known incidents in which an Agile Fighter re-entered the atmosphere unassisted both resulted in crashes that either heavily damaged or completely destroyed the ships in question, this has not been definitively confirmed.

In addition to their surreal handling, maneuverability, and their ability to travel into space unassisted, each Agile Fighter possesses the infinitely more valuable ability to produce and envelope itself in a working particle shield that deflects all incoming physical projectiles from space debris, to small-arms fire, all the way up to one or more successive direct hits from highly explosive air-to-air missiles or 20mm auto-cannon fire. This crucial edge gives the Agile Fighter survivability, thereby turning it into the perfect air-interceptor, allowing it to return to base only lightly or perhaps even entirely undamaged.

It is highly evident that the method that allows each Attack craft to produce enough energy to power both the propulsion, internal avionics, life-support, and weapons systems in addition to maintaining a working constant-use or even multi-use shielding system, requires an energy source or conversion process several orders more powerful than combustion engines or perhaps even nuclear fusion could match. Despite the best efforts of Area 51's scientists over nearly 50 years of dedicated study and reverse-engineering, no similar power plant could be replicated to power a salvaged Attacker craft. Ironically, during the arrival of the aliens during the War of 1996, the crashed craft spontaneously re-activated, thus leading to speculation that Agile Fighters may actually receive some or all of their energy remotely from a power plant aboard the City destroyers or Colony ships.

Deployment and combat capabilities
Owing to their tremendous technological advancement, stock Agile Fighters make exceedingly lethal fighter-interceptors alone, and are nearly unstoppable when deployed in groups from inside City Destroyer craft, which also serve as aircraft carriers. In combat, the preferred tactic used by the aliens is to deploy massive swarms of Agile Fighters directly from the interior of a Destroyer, and secure absolute air dominance by crushing opponents with sheer numbers. Faced with 3 or even 4-to-1 odds or more, engagements are often brutally short and very one-sided; against an unshielded foe, Attacker craft can quickly destroy enough enemy units that the remaining few are exponentially overwhelmed, eventually facing odds of an entire squadron of Agile Fighters per single enemy unit.

In the Expanded Universe novel Independence Day: War in the Desert, a City Destroyer in the Middle East deploys five hundred Agile Fighters to destroy the Earth fighters, and a large (unspecified) number of additional Fighters are found inside the ship after it crashes. The hangar of a City Destroyer therefore has a capacity of at least five hundred attacker craft, and given its massive size relative to one fighter, the theoretical hangar space to host many more.

War of 1996
Attackers were deployed after the Harvesters began their attack on Earth and met with retaliation by human military forces. Like the City Destroyers, the Attackers were equipped with deflector shields and allowing them to easily decimate human forces without losses. Although few Attackers did suffered casualties, such as U.S. Force Captain Steven Hiller by evading an Attacker and luring it into the Grand Canyon, where he caused the spacecraft to crash through solid rock.

On day of "The Fourth", the Attackers' deflector shields were disabled by David Levinson's computer virus, and were then forced into a even battle against human fighters and lose. Their remains were likely cannibalized in the aftermath.