Taliban officials said U.S. negotiators Saturday agreed on a draft peace pact setting out the withdrawal of foreign troops from Afghanistan within 18 months, potentially ending the longest war of the U.S..

The details of the draft were given to Reuters by Taliban sources at the end of six days of talks with U.S. Special Peace Envoy Zalmay Khalilzad in Qatar aimed at ending the war, more than 17 years since American-led forces invaded Afghanistan. It stipulates that troops would leave within 18 months of the agreement being signed.

While no joint statement was issued, Khalilzad tweeted later that the talks had made "significant progress" and would resume shortly, adding that he planned to travel to Afghanistan to meet government officials.

"Meetings here (in Qatar) were more productive than they have been in the past. We have made significant progress on vital issues," he wrote, adding that numerous issues still needed work.

"Nothing is agreed until everything is agreed and everything must include an intra-Afghan dialogue and comprehensive ceasefire," he wrote in the tweets.

U.S. Secretary of State Mike Pompeo Saturday also described the progress achieved with Taliban an "encouraging news" in his twitter, adding that the U.S. is serious about pursuing peace in Afghanistan and bringing the U.S. forces home.

He did not give a timetable for the potential withdrawal of U.S. forces. 

A Taliban statement issued later also noted progress on troop withdrawal and other issues but said more negotiations and internal consultations were required. "The policy of the Islamic Emirate during talks was very clear -- until the issue of withdrawal of foreign forces from Afghanistan is agreed upon, progress in other issues is impossible," said Taliban spokesman Zabihullah Mujahid, using another name the group calls itself.

It was not clear whether the draft described by the Taliban sources was acceptable to both sides or when it could be completed and signed.

According to the sources, the hard-line Islamic group gave assurances that Afghanistan will not be allowed to be used by al-Qaeda and ISIL militants to attack the United States and its allies -- a key early demand of Washington.

Taliban said the deal included a ceasefire provision but they had yet to confirm a timeline and would only open talks with Afghan representatives once a truce was implemented. Up until now, the Taliban has repeatedly rejected the Afghan government's offer of holding talks, preferring instead to talk directly to the U.S. side, which it regards as its main enemy.

"In 18 months, if the foreign forces are withdrawn and the ceasefire is implemented, then other aspects of the peace process can be put into action," a Taliban source said, quoting from a portion of the draft.

Taliban expect their side to be led by new political chief Mullah Abdul Ghani Baradar, the movement's co-founder and a former military commander who was released from prison in Pakistan last year. While they said his appointment had boosted momentum for a deal, it was unclear if he had joined the talks.

More talks on the draft are expected in February, again in the Qatari capital Doha, the Taliban sources said.

(Top photo: Afghan President Ashraf Ghani (top R) meets with U.S. Defense Secretary James Mattis (C), U.S. Ambassador to Afghanistan John Bass (2nd L), and U.S. General Joseph Dunford at the Presidential Palace in Kabul, September 7, 2018. /VCG Photo)