success as a patrol and interceptor aircraft. During the seventies and early eighties an additional 20 or more T-33s were procured by the FAM to replace aircraft lost in accidents and to increase the size of the fleet after the retirement of the Vampires. In 1982, the FAM received 12 Northrop F-5E/F Tiger II jets (10 F-5Es and 2 F-5Fs). The F-5 gave Mexico its first supersonic platform and saw the formation of Air Squadron 401. Since the 1980s the F-5 became the main Mexican fighter jet while the remaining operational T-33s were used for subsonic support and light attack roles. In 1983 one F-5E was lost in an accident that occurred during a target practice exercise in the state of Chihuahua. Chiapas conflict On January 1, 1994, the day the North American Free Trade Agreement (NAFTA) came into effect, hundreds of guerrillas from the previously unknown Zapatista Army of National Liberation (EZLN) occupied several towns and cities in the southern state of Chiapas. The FAM was mobilized to support Army units, sending almost every available helicopter to the territory of operations. Units involved included the recently formed 214th and 215th Special Operations Squadrons, equipped with a mix of Bell 212 assault- and MD.530F scout helicopters. Up to 40 helicopters were deployed to support an initial deployment of 10,000 ground troops. Bell 212s were armed in two configurations: for fire support with twin MAG 7.62-mm gun pods and cabin-mounted GPMGs; or as gunship, with LAU-32 70-mm rocket launchers, a twin MAG gun-pod and cabin mounted MAG GPMGs. Pumas, Bell 205s, 206s and 212s from the 209th were also deployed, however, FAM's helicopter assets were scarce and the Mexican Army had to rely on almost every other government agency's helicopters for general support tasks. Almost any flyable aircraft from the National Attorney's Office (PGR) was also deployed, including Bell 206s and 212s, as well as the Navy's recently acquired Mi-8MTV-1s. Eventually the Army deployed some 70,000 ground troops and air support proved to be insufficient; hence the decision was taken to considerably expand the FAM's helicopter fleet. By December 1994, FAM had bought additional 12 armed MD.530MG 'Defender' and four UH-60L Blackhawk helicopters, which it grouped into the 216th Special Operations Squadron. This unit was the spearhead of operation "Arco Iris" (Rainbow) to re-take several towns that had fallen under rebel control in January 1994. The new militarized Defenders came armed