Agence France-Presse also cited a Turkish presidential source as saying the leaders "agreed to ensure more effective cooperation on the subject of Syria". The call followed contacts earlier this week between Secretary of State Mike Pompeo and Joint Chiefs of Staff Chairman Joseph Dunford Jr. and their Turkish counterparts.
Fighting against the Islamic State group in its last enclave in eastern Syria "is going very well", a USA official said Saturday as US -backed Syrian fighters battled the extremists on the edge of the largest urban area they still hold. It is known by the US military as the Syrian Defense Forces, or SDF. Turkey says the YPG is a terrorist organization and an extension of the outlawed Kurdistan Workers Party (PKK).
Tense relations between Turkey and the United States are at the heart of this dilemma. The official expressed some optimism, following the high-level calls, that ongoing US and North Atlantic Treaty Organisation efforts to address Ankara's concerns would calm the situation.
The Islamic State has been driven from almost all the territory it once held in Syria a year ago in separate campaigns waged by the US-backed SDF on the one hand, and the Russian-backed Syrian government on the other.
The mosque was located in the town of Hajin, eastern Syria, and was known to have been used by 16 heavily armed Islamic State terrorists as a base.
The operation was completed at dawn, a day after SDF forces fanned out across the town in the Euphrates valley, he said.
He also stressed that all the Free Syrian Army members stand ready to cooperate and join in the upcoming military operation.
"Now that we are inside the city of Hajin and about to eliminate Isis, they [Turkey] rush into its defence", said a spokesperson for a Kurdish Syrian militant group which is part of the US-backed Syrian Democratic Forces (SDF).
The US Department of Defense (DoD) indicated on 12 December that it is seriously concerned about a Turkish military operation into northeast Syria, publicly warning Ankara that this would be "unacceptable". There are very few of them left in that area of the world.
Erdogan dismissed that description as false.
"We are not only providing security for our country when taking steps in Syria but we are also protecting the honor of people", he said.
"We know the Arabs well, but we know terrorist Kurds as well", Erdogan said in a blunt statement that made Turkey's essentially anti-Kurdish policy all too apparent in contrast to the official rhetoric of "fighting terrorism".
In a statement Friday, the USA coalition command repeated that the observation posts were to "address the security concerns" of Turkey, and that any reports stating otherwise were "false and created to sow confusion and chaos".