The decision to open the Taliban office was a reversal of months of failed efforts to start peace talks while the militants intensified a campaign targeting urban centers and government installations.
Experts warned that it would be a mistake to expect too much.
"The keys are to keep expectations low, to remember that a compromise is unlikely because no one can say what it would consist of," said Michael O'Hanlon of the Brookings Institution. He added that in his opinion, the Taliban wrongly "expect to win the war once NATO is largely gone come 2015."
"All that said, it's a potentially useful step if we don't confuse ourselves or wind up in polarizing debates within the coalition," O'Hanlon said.
In Doha, Ali Bin Fahad Al-Hajri, the assistant to the foreign minister of Qatar, said the Emir of the Gulf state had given the go-ahead for the office to open.
"Negotiations are the only way for peace in Afghanistan," Al-Hajri said.
The Taliban emerged from the Pakistani-trained mujahedeen, or holy warriors, who battled the Soviet Union's occupation of Afghanistan in the 1980s with secret backing by the CIA. Civil war broke out when the pro-Soviet Afghan government collapsed following the departure of Moscow's troops. The U.S. took an arms-length position of neutrality as rival warlords shelled Kabul into ruins.
By 1994, the Taliban had evolved into a united military and political force and in 1996, the group took control of Afghanistan. Led by Mullah Mohammed Omar, the Afghan Taliban sheltered Osama bin Laden in the years leading up to the Sept. 11 attacks in 2001, but the group was toppled shortly after the U.S. and allied invasion one month later.
The U.S.-led invasion leveraged the firepower of factions, such as the Northern Alliance, who had held out against the Taliban after it seized power in 1996. CIA and U.S. special operations support for anti-Taliban forces enabled the U.S. to oust the Islamists by December 2001 without committing large numbers of U.S. ground troops, and the group appeared to have been defeated as a military threat.
However, by 2005, the Taliban was beginning to make a comeback, showing signs of improved training and equipment, while using territory inside Pakistan as a sanctuary.
On Monday, Taliban spokesman Mohammad Naim said the Islamic Emirate of Afghanistan, as the Taliban were known when they ruled the country, was willing to use all legal means to end what they called the occupation of Afghanistan. But he did not say they would immediately stop fighting.
"The jihad continues to end the occupation and establish an Islamic emirate. To achieve this goal, we will follow every legitimate means," he said. "The emirate of the Taliban, with its military effort, has a strategic goal related to the future of Afghanistan. The movement is not intending to harm any other parties and will not allow anybody to use Afghan territory to threaten other countries."
The Obama administration officials said the U.S. and Taliban representatives will hold bilateral meetings. Karzai's High Peace Council is expected to follow up with its own talks with the Taliban a few days later.
But in making their announcement in Doha, the Taliban did not specifically mention talks with Karzai or his representatives.
"We don't recognize the Afghan government and the government of Karzai. The talks will be with the Americans only in Doha under the patronage of Qatar," he said. "We represent the people of Afghanistan. We don't represent the Karzai government."
The administration officials acknowledged the process will be "complex, long and messy" because of the ongoing level of distrust between the parties.
The officials, who spoke on condition of anonymity because they were not authorized to speak on the record, vowed to continue to push the Taliban further, saying that the Taliban ultimately must also break ties with al-Qaida, end violence and accept Afghanistan's constitution — including protections for women and minorities.
They said the U.S. had long demanded that the Taliban make a statement distancing the group from international terrorism, but had said that they did not expect them to break ties with al-Qaida immediately. That would be one of the outcomes of the negotiating process, they added.