With the breakup of the Soviet Union in 1991, the Soviet-supported government of Najibullah lost credibility. In 1992, Russia agreed to end fuel shipments to Afghanistan, which triggered the collapse of Najibullah's regime. In April 1992, General Abdul Rashid Dostum defected to the forces of Ahmed Shah Massoud, and began to take control of Kabul. By April 14, 1992, Massoud and his forces took control of Charikar and Jabalussaraj in Parwan province without significant fighting. At this point, it was reported that Massoud had approximately 20,000 troops stationed around Kabul. It was also reported that the government's Second Division had joined Massoud. General Mohammad Nabil Azimi then proceeded to reinforce Bagram Air Base, and sent further reinforcements to the outer perimeter of Kabul. By mid-April, the air force command at Bagram capitulated to Massoud. With no army to defend it, Kabul had become completely helpless.