Ankara is concerned about US plans to set up observation posts in Syria along parts of its border with Turkey, according to Turkish Defence Minister Hulusi Akar.
He said that during a recent visit to Canada, he told US Chief of Staff Joseph Dunford that setting up the posts would have "a very negative impact" on perception of the United States in Turkey.
"During our talks with both political and civilian interlocutors we repeatedly expressed our unease in various ways. I think actions like this will make the complicated situation in the region even more complicated," Akar pointed out.
He added that during the course of the discussions, the Turkish side noted that "it seems as if the US military is somehow protecting terrorists from the Kurdish self-defence units (YPG) and covering them".
"We expect our US allies to immediately cut their ties with the terrorist YPG, who are not in the slightest bit different from the PKK [The Kurdistan Workers' Party]," Akar said, pledging that Ankara will take "the necessary steps against all kinds of risks and threats from across its borders".
He remarks came after US Defence Secretary James Mattis said that the US military is setting up several observation posts in Syria beside the border with Turkey.
He said that the goal is to provide Ankara with "military intelligence of any terrorist elements moving into Turkey from Syria.
Washington disagrees with Ankara over US support for the Kurdish-led opposition Syrian Democratic Forces (SDF), which Ankara considers to be linked with the Kurdistan Workers' Party (PKK) and has blacklisted as a terror group.
According to the White House, the mission's purpose is to support the US commitments to its NATO ally Turkey.