Foreign Minister Mevlüt Çavuşoğlu and U.S. Secretary of State John Kerry discussed the recent developments in Syria the in a phone call on Saturday.

According to diplomatic sources, the two leaders agreed that the ongoing violence must come to an end as soon as possible and talked about the timeline for the meetings about a political transaction process that the two countries will hold soon.​

The northern Syrian city of Aleppo -- the country's largest city before the war -- has been subject to an intense air campaign by Syrian and Russian warplanes amid clashes between forces allied to the Syrian regime and opposition forces.

Scores of civilians have reportedly been killed or injured in the attacks, which remain ongoing.

Syria has been locked in a vicious civil war since 2011, when the Bashar al-Assad regime cracked down on pro-democracy protests-which had erupted as part of the Arab Spring uprisings-with unexpected ferocity.

The Syrian Center for Policy Research, a Beirut-based nongovernmental organization, has put the death toll from the six-year-old conflict at more than 470,000.