Turkey expects President Donald Trump to use a waiver to protect it if the U.S. Congress decides to sanction Ankara over a planned purchase of a Russian missile defense system, a Turkish presidential spokesman said in Washington on Tuesday.

The United States has threatened to impose sanctions if Turkey seals its deal with Russia. Ankara has said its purchase should not trigger sanctions as Turkey is not an adversary of Washington and remains committed to the NATO alliance.

“If it comes to that, that is the sanctions proposed to be implemented by the Congress, of course we will expect President Trump to use his power for a waiver on that issue,” Ibrahim Kalin told reporters in a briefing.

Asked if Trump has explicitly signaled he would issue a waiver, Kalin said he did not. “I cannot say that he did. This is a message we are conveying.”

U.S. officials have called Turkey’s planned purchase of Russian-made S-400 missile defense systems “deeply problematic,” saying it would compromise the security of F-35 fighters jets, made by Lockheed Martin Corp. Turkey has refused to back down and said it will take delivery of the S-400s in July.

The disagreement is the latest in a series of diplomatic disputes between the United States and Turkey. They include Turkish demands that Washington extradite cleric Fethullah Gulen, differences over Middle East policy and the war in Syria, and sanctions on Iran.

Asked what Turkey would do if Trump abstained from providing a waiver, Kalin said Turkey would have to wait and see the scope of the sanctions, but hopes it does not come to that.

“Threats and sanctions would be very counterproductive, backfire and will not produce any results positively,” he said.