The Gundam GP02A, code-named "Physalis," is the second of the prototype mobile suits developed by Anaheim Electronics as part of the Gundam Development Project. Unlike the general-purpose GP01, the GP02A was created specifically to use tactical nuclear weapons. Its "atomic bazooka" is designed to fire Mk. 82 warheads, and the Gundam's huge shield not only adds to its heavy armor, but also incorporates powerful cooling systems to protect it from the heat of a nuclear blast. The existence of the Gundam GP02A is in itself a violation of the wartime Antarctic Treaty, which prohibited the development and use of nuclear weapons.

The Gundam was also heavily armored enough to withstand the nuclear blast unleashed by its bazooka, and even carried a shield large enough to provide extra protection for most of the unit's body and contained cooling systems to help dissipate the heat it would absorb. The shield also carried the trigger and barrel for the atomic bazooka when it was no deployed for use. Moreover, the GP02A was designed to survive in close combat, being armed with standard head vulcan guns and a pair of beam sabers. With enough thrusters and verniers to keep it fast and agile despite its mass, the Gundam GP02A was truly "tactical" in a sense, though its use would have "strategic" consequences for the Earth Sphere. The Gundam GP02A was completed at Anaheim's Von Braun factory on September 18, UC 0083, and in early October it's sent to the Federal Forces' Torrington base in Australia for field testing. On October 13, soon after being loaded with a live warhead from Torrington's nuclear stockpiles, the GP02A is stolen by Delaz Fleet ace pilot Anavel Gato.

Source: Gundamproject.com, Gundam 0083 Visual Comic