Turkey's foreign minister has assured his Iranian counterpart that Ankara's military operation in northern Syria, which began on Monday night, is a temporary one.

Turkey's Mevlut Cavusoglu gave the assurance in a Monday phone conversation with Iranian Foreign Minister Mohammad Javad Zarif, as Turkish troops started their operation against Syrian Kurds in the Arab country's north.

Local sources report the Turkish military has just started shelling the positions of the People's Protection Units (YPG), a Syrian Kurdish group that Turkey claims to be linked to PKK terrorists, in northern Syria's al-Malikiyah town in the north of Hasakah.

In the phone call with Zarif, Cavusoglu emphasized the need to respect Syria’s territorial integrity, saying Turkey’s operation in that region would be temporary.

The Iranian top diplomat, however, expressed Tehran's opposition to any military action, and urged Turkey to respect the territorial integrity and national sovereignty of the Arab country.

Zarif at the same time stressed the necessity of fighting terrorism in Syria for the ultimate establishment of stability and security at the country. However, he said the Adana Agreement is the best approach for Syria and Turkey to address their concerns.

The Adana Interstate Agreement on Combating Terrorism was signed between Turkey and Syria on October 20, 1998. It clearly stated that the Damascus government would not allow any activities of the Kurdistan Workers’ Party (PKK) militant group on Syrian soil, and would block any terror activities that could threaten Turkey's sovereignty.

The Turkish operation started after the US in a major shift in its policy gave the green light to Turkey to launch a military operation against Washington's long-time Kurdish allies in northern Syria.

“Turkey will soon be moving forward with its long-planned operation into northern Syria,” the White House said in a statement after a phone call between US and Turkish presidents.

Following the decision, Zarif tweeted that the United States is an "irrelevant occupier in Syria," stressing that peace will be achieved in the war-ravaged country only through respect for its territorial integrity and people.

"US is an irrelevant occupier in Syria—futile to seek its permission or rely on it for security," Zarif said in a post on his official Twitter account on Monday, after the US gave the green light to Turkey to launch a military operation in northern Syria.

Ankara had been threatening for months to launch an offensive in northern Syria against the US-backed Kurdish forces there.

US soldiers had worked closely with Kurdish forces of the so-called Syrian Democratic Forces (SDF), led by militants from the YPG , in a battle with the declared aim of destroying Daesh.

Turkey considers the YPG a terrorist organization and an extension of the PKK, which has been fighting for an autonomous region inside Turkey since 1984.