even SAS training grounds in the Scottish Highlands. These forces were divided into different types of units: the locals (mahalli) were tasked with static defense of villages and fortified positions. The best of the mahalli were formed into units called grup-i zarbati (shock troops), semi-mobile groups that acted as reserve forces for the defense of several strongholds. A different type of unit was the mobile group (grup-i-mutaharek), a lightly equipped commando-like formation numbering 33 men, whose mission was to carry out hit-and-run attacks outside the Panjshir, sometimes as far as 100 km from their base. These men were professional soldiers, well-paid and trained, and, from 1983 on, they provided an effective strike force against government outposts. Uniquely among the mujahideen, these groups wore uniforms, and their use of the pakul made this headwear emblematic of the Afghan resistance. Massoud's military organization was an effective compromise between the traditional Afghan method of warfare and the modern principles of guerrilla warfare which he had learned from the works of Mao Zedong and Che Guevara. His forces were considered the most effective of all the various Afghan resistance movements. The Soviet army and the Afghan communist army were mainly defeated by Massoud and his mujahideen in numerous small engagements between 1984 and 1988. After describing the Soviet Union's military engagement in Afghanistan as "a bleeding wound" in 1986, Soviet General Secretary Mikhail Gorbachev began a withdrawal of Soviet troops from the nation in May 1988. On February 15, 1989, in what was depicted as an improbable victory for the mujahideen, the last Soviet soldier left the nation. Fall of the Afghan communist regime (1992) After the departure of Soviet troops in 1989, the People's Democratic Party of Afghanistan regime, then headed by Mohammad Najibullah, held its own against the mujahideen. Backed by a massive influx of weapons from the Soviet Union, the Afghan armed forces reached a level of performance they had never reached under direct Soviet tutelage. They maintained control over all of Afghanistan's major cities. During late 1990, helped by hundreds of mujahideen forces, Massoud targeted the Tajik Supreme Soviet, trying to oust communism from the neighboring Tajikistan to further destabilize the dying Soviet Union, which would also impact the Afghan government. At that time, as per Asad Durrani, the director-general of the ISI during this period, Massoud's base camp was in Garam Chashma, in Pakistan. By 1992, after the collapse