Turkey's ground operation in Syria in support of the Free Syrian Army (FSA) is in Ankara's national security interest, the U.S. State Department said Wednesday.

"Actions that we carry out against DAESH in Syria is, we believe, in the national security interests of the United States and our allies and our partners," agency spokesman Mark Toner said. "I think Turkey would also make the case, if I'm guessing, that it's also in their national security interest to protect and drive ISIL [DAESH] away from their border." The comments come amid complaints from Moscow about the expansion of the Turkey-led Operation Euphrates Shield along its border inside Syria.

The Russian foreign ministry expressed its concerns about the mission, noting that it is not sanctioned by the U.N. Security Council or was consented to by the regime of Syrian President Bashar Assad. Turkey, as well as the U.S., has long said the government in Damascus has lost its legitimacy as it has killed more than 400,000 people, displacing nearly 10 million others, according to U.N. numbers.

Russia's concerns come just a few months after Moscow and Ankara mended strained ties after Turkey shot down a Russian fighter jet that entered Turkish air space along the Syrian border late last year. Toner confirmed that Secretary of State John Kerry spoke with Russian Foreign Minister Sergey Lavrov via telephone earlier Wednesday but he would not confirm reports that the two diplomats would meet later this week in Geneva to discuss a potential cease-fire in Syria.

"The secretary remains committed to continuing efforts to try and resolve the remaining or outstanding issues in order to reach an arrangement on Syria that will put in place a durable cease-fire - cessation of hostilities; provide humanitarian access to all areas; and lead to a resumption of talks between parties in Geneva," he said.