By Ahmet Gurhan Kartal
U.S. Secretary of State Rex Tillerson said on Monday Washington recognizes and fully appreciates Turkey's legitimate right to protect its citizens from terrorist elements.
His remarks came during a meeting with British Foreign Secretary Boris Johnson in London.
He said the Daesh terror group in Syria had been defeated.
"So we are concerned about the Turkish incidents in northern Syria," Tillerson said.
"We recognize and fully appreciate Turkey's legitimate right to protect its own citizens from terrorist elements that may be launching attacks against Turkish citizens on Turkish soil from Syria," he added, also urging all sides to show restraint.
Tillerson said he was in talks with Ankara and the leadership of the US-led coalition in Syria, adding that he was hoping to address Turkey's "legitimate concerns".
Turkey on Saturday launched Operation Olive Branch to remove PYD/PKK and Daesh terrorists from Afrin.
According to Turkish General Staff, the operation aims to establish security and stability along Turkish borders and the region as well as to protect the Syrian people from the oppression and cruelty of terrorists.
The operation is being carried out under the framework of Turkey’s rights based on international law, UN Security Council’s decisions, self-defense rights under the UN charter and respect to Syria's territorial integrity, it said.
The military also said the "utmost importance" was being given to not harm any civilian.
Afrin has been a major hideout for the PYD/PKK since July 2012 when the Assad regime in Syria left the city to the terror group without putting up a fight.
Later on Monday, Tillerson and Johnson held a closed-door meeting.
Tillerson also met Prime Minister Theresa May and National Security Adviser Mark Sedwill.