Alarmed by the deteriorating situation, especially the collapse of the army and the prospect that a disintegrating Afghanistan would threaten its security on its southern border, the Soviet Union airlifted thousands of troops into Kabul on December 24, 1979. The Khalq president, Hafizullah Amin, was assassinated after Soviet intelligence forces took control of the government and installed Babrak Karmal, a Parchami, as president.
The Soviet occupation force of some 115,000 troops and the Karmal government sought to crush the uprisings with mass arrests, torture, and executions of dissidents, and aerial bombardments and executions in the countryside. Some one million Afghans died during this period, most in aerial bombardments. These measures further expanded the resistance to the communist government in Kabul and fueled a flow of refugees out of the country that soon reached five million out of a population of about sixteen million.
Islamist organizations that became the heart of the resistance - and collectively became known as the jihad fighters or mujahidin - based themselves in Pakistan and Iran.. Seeing the conflict as a cold war battleground, the United States and Saudi Arabia, in particular, provided massive support for the resistance, nearly all of it funneled through Pakistan. The arms pipeline gave Pakistan a tremendous ability to bolster parties in Afghanistan that would serve its own interests.
Joining the resistance forces were thousands of Muslim radicals from the Middle East, North Africa and other Muslim countries. Most fought with Pashtun factions that had the strongest support from Pakistan and Saudi Arabia, the Hizb-i Islami of Gulbuddin Hikmatyar and Ittihad-i Islami of Abdul Rasul Sayyaf. Among them was Osama bin Laden, who came to Pakistan in the early 1980s and built training facilities for these foreign recruits inside Afghanistan.
