(File photo: VCG)

WASHINGTON, July 20 (Xinhua) -- U.S. Secretary of State Mike Pompeo spoke over the phone on Saturday with Turkish Foreign Minister Mevlut Cavusoglu regarding their dispute over S-400 deal and security along the Turkey-Syria border.

In their phone conversation, Pompeo conveyed the U.S. disappointment over Turkey's acquisition of the Russian S-400 air defense system, State Department spokesperson Morgan Ortagus said in a statement.

Pompeo reaffirmed to Cavusoglu the U.S. commitment to addressing Turkish security concerns along the Turkey-Syria border, while reiterating the U.S. obligation to ensure the protection of local partners working with the United States in the campaign against the Islamic State, referring to Kurdish forces.

Ankara has long designated Syrian Kurdish fighters as terrorists. Turkish media reported earlier this month that a large Turkish military convoy was sent and deployed in the southern province of Hatay near the Syrian border, leading to speculation that a Turkish offensive against Kurdish forces might be imminent.

The White House and the Pentagon confirmed earlier this week that Turkey's purchase of S-400 systems had led to the termination of Ankara's involvement with the F-35 program.

Turkish Foreign Ministry on Wednesday called the U.S. move to terminate Turkey's participation in the F-35 program illegitimate and might bring irreparable damage to bilateral relations.