U.S. Secretary of State Mike Pompeo said Friday that talks between the U.S. and Turkey earlier in the week had led to "important progress" toward establishing a safe zone in northern Syria.

"Pleased that talks between the U.S. & Turkey led to important progress towards establishing a sustainable security mechanism to address our shared security concerns in Northeast #Syria," the top U.S. envoy wrote on Twitter.

"Establishing a safe zone would be a big step towards achieving peace & security," he added.

On Wednesday, Turkish military officials and their U.S. counterparts agreed that a safe zone in northern Syria would be a "peace corridor" for displaced Syrians longing to return home.

Both sides also agreed on the immediate implementation of measures to address Turkey's security concern.

The officials also planned for a Joint Operations Center to be established in Turkey to coordinate and manage the establishment of the safe zone.

Turkey expects the creation of a 32-kilometer (20-mile) safe zone in northern Syria, which must be cleared of the People's Protection Units (YPG), the Syrian branch of the PKK. Ankara has warned that if establishment of such a zone is delayed, it will take cross-border military action to remove the terrorist threat at its southern border.

The U.S. has primarily partnered with the Syrian Democratic Forces (SDF), an umbrella organization in northeastern Syria in the anti-Daesh fight. The SDF is led by the YPG, the Syrian branch of the PKK, a designated terrorist organization in the U.S. and Turkey.

Turkey strongly opposes the YPG's presence in Manbij, which has been a major sticking point in strained Turkey-U.S. relations due to the latter's support for the YPG under the pretext of fighting Daesh. The U.S. has provided military training and given truckloads of military support to the YPG, despite its NATO ally's security concerns.

To reduce tensions, Turkey and the U.S. agreed on a road map in June 2018 foreseeing the withdrawal of the YPG from Manbij and installing joint Turkish-American patrols, which began in November. However, the process has been sluggish as the terrorist group was still present in the city despite the three-month timetable set for implementing the deal.

Turkey previously carried out two cross-border operations west of the Euphrates River, Operation Euphrates Shield launched in August 2016 and Operation Olive Branch in January 2018, to drive terrorist groups, including the YPG and Daesh, from its borders.