KABUL/ISLAMABAD (Reuters) – Talks to end the 18-year-old conflict in Afghanistan may begin this month, sources said on Monday, a day after the U.S. special envoy visited the capital of neighbouring Pakistan and met Taliban leaders in Qatar.

The United States signed a troop withdrawal deal with the Taliban in February, but its attempts to usher the insurgent group towards peace talks with the Afghan government have been mired in setbacks and violence surged in March and April.

The Taliban’s spokesman Suhail Shaheen said on Twitter that U.S. envoy Zalmay Khalilzad had discussed “the commencement of intra-Afghan negotiations” at the insurgent group’s political capital, Doha, on Sunday. Khalilzad had earlier met Pakistan’s army chief of staff, according to the U.S. Embassy in Islamabad.

“The two took note of recent progress created by the Eid ceasefire and accelerated prisoner releases as well as reduced violence ahead of intra-Afghan negotiations,” the Embassy said on Monday. “(They) discussed steps required for the start of intra-Afghan negotiations.”

Disagreement over the Taliban’s demand for the release of 5,000 prisoners has also blocked progress towards resolving the conflict, in which Pakistan is considered a key regional player.

One Afghan presidential palace source and one diplomatic source told Reuters those issues were gradually being resolved and momentum had grown in recent weeks for formal talks, which were expected to begin this month, likely in Doha.

However the sources also told Reuters that due to complications from the coronavirus some negotiations might initially be held virtually.

“The ceasefire, prisoners release and reduction in violence has created a momentum for the talks to begin soon and the government is fully ready,” the Afghan palace official told Reuters, adding that President Ashraf Ghani was optimistic.