U.S. diplomats and the Afghan Taliban have seen cause for hope in talks to end the United States' longest war, but the pivotal issues of a ceasefire and the militants sitting down with the Afghan government are far from being resolved.

Areas in which both sides have hailed progress, plans for the withdrawal of foreign troops 17 years after the U.S.-led ouster of the Taliban and assurances that Afghanistan won't become a base for al-Qaida or Daesh, still need detailed negotiation, sources on both sides said.

The withdrawal, for example, is contingent on a ceasefire that the Taliban have yet to discuss. "We want to be absolutely sure that the U.S. is leaving before we call off the fight," said a senior Taliban official on condition of anonymity. But a senior U.S. official privy to the negotiations was clear a ceasefire had to come first: "How could we even do a withdrawal without a ceasefire?"

And the Taliban's assurances on counter-terrorism also come with caveats. They say they can guarantee the United States the security of the half of the country they now control, but they would have to be in an interim government to be sure of stopping al-Qaida or Daesh from attacking anywhere else.

Left to watch the unlikely U.S. and Taliban tango as he eyes a second term, Western-backed Afghan President Ashraf Ghani refuses to accept an interim government as part of any deal. "We want peace, we want it quickly, but we want a proper plan ... so the mistakes of the past do not repeat," Ghani said in a televised address on Monday, referring to a bloody history of failed governments, military coups and civil war. Ghani mentioned the deaths of previous rulers, including former President Najibullah, who was hanged from a Kabul lamppost when Taliban guerrillas swept into the capital in 1996.

The next round of talks will be held in Qatar on Feb. 25 when Mullah Abdul Ghani Baradar, a former mujahideen fighter against the Soviet occupation of the 1980s, will head the Taliban side following his release last year from eight years in a Pakistani jail.

U.S. officials told Reuters they hope he will have the authority to negotiate on the ceasefire and the need for discussions with the Afghan government. The Taliban have so far refused to talk to the government which they dismiss as a puppet of the United States.

Doubts have increased in recent weeks whether U.S. President Donald Trump would stomach a protracted presence in Afghanistan amid mixed signals from Washington. U.S. officials told Reuters last month that Trump had issued verbal orders to plan for a withdrawal of about half of the 14,000 U.S. troops in Afghanistan. However, they said he could reverse course.

The U.S. troops in Afghanistan are part of a NATO-led mission and a U.S. counterterrorism mission largely directed at groups such as Daesh and al-Qaida. Some 8,000 troops from 38 other countries are participating in the operation, known as Resolute Support. Diplomats and military attaches from many of those countries describe an intense desire to leave. Italy is considering sending home its 900 troops within a year.