When the Soviet Union invaded in 1979, a group of Afghan Muslims declared a holy war. They were known as the Mujahedeen.
"The term Mujahedeen derives from the word jihad - the holy struggle," said Michael Semple of the Kennedy School of Government.
They shared a common enemy with the United States and both the Carter and Reagan administrations gave the Mujahadeen $3 billion in military aid to fight the Soviets, reports CBS Evening News anchor Katie Couric.
"Any form of assistance that they could think of, the United States administrations provided," Semple said.
All while the Mujahedeen were celebrated as freedom fighters, standing shoulder to shoulder with James Bond and Rambo in Hollywood films.
The Soviets withdrew - defeated - in 1989. But the mujahedeen could not secure peace. The country quickly disintegrated into civil war. And with the Russians gone, the Americans lost interest in Afghanistan.
"We withdrew," said Secretary of State Hillary Clinton. "And we left the problems of a well-equipped, fundamentalist, ideological and religious group that had been battle-hardened to the Afghans and the Pakistanis."
The most militant, extremist faction of the Mujahideen turned into the Taliban.
"The Taliban emerged as this kind of altruistic group which wanted to bring peace to Afghanistan and initially they were very popular," said Pakistani journalist Ahmed Rashid.
But the Taliban's fight to be more powerful than the Mujahadeen cost money. And a wealthy Saudi Arabian exile, in need of safe haven, stepped up as the Taliban's banker.
"Osama Bin Laden completely ingratiates himself with the Taliban," Rashid said. "He provides them with money, fighters, reconstruction efforts. So he's a great asset to them."
Less than a month after the 9/11 attacks, President Bush issued an ultimatum to the Taliban: turn over Osama bin Laden, or face the consequences.
"None of these demands were met. And now the Taliban will pay a price," Bush said in 2001.
Although the U.S. and its Afghan allies did topple the Taliban, a fateful strategic error cost the coalition its prize. In November 2001, bin Laden was cornered in the Tora Bora mountains along the Pakistani border. But the U.S. chose not to act and instead outsourced the capture of the al Qaeda leader to local Afghan militias.
Bin Laden escaped - and the trail has been cold ever since.
More special coverage on CBSNews.com:
Marines in Afghanistan: A Day in the Life
Taliban Gaining Firepower and Confidence
Battle of Wanat - Inside the Ambush
Afghanistan, 8 Years In: How We Got Here
McCain, Kerry Answer Key Questions on Afghanistan
Public's Views of Afghanistan War Have Turned Sour