WASHINGTON (Reuters) - The United States continues to object “strenuously” to Turkey’s purchase of Russian missile defense systems and is “deeply concerned” with reports that Ankara is continuing its efforts to make the weapons operational, U.S. State Department spokeswoman Morgan Ortagus told Reuters on Monday.

“We continue to stress at the highest levels that the S-400 transaction is the subject of ongoing CAATSA sanctions deliberations and it remains a major obstacle in the bilateral relationship and at NATO. We are confident that President Erdogan and his senior officials understand our position,” Ortagus said in an emailed statement.