The United States banned all US export licenses and loan credits for the agency, the Presidency of Defense Industries. It said it would not allow its president, Ismail Demir, to travel or hold assets in the United States.

The US Congress required sanctions for significant military purchases from Russia under a 2017 law known as CAATSA, but Trump had previously voiced sympathy for Turkish President Recep Tayyip Erdogan, who has warned that sanctions would be “disrespectful.”

“Today’s action sends a clear signal that the United States will fully implement CAATSA Section 231 and will not tolerate significant transactions with Russia’s defense and intelligence sectors,” Secretary of State Mike Pompeo said in a statement.

Turkey took delivery of the $2.5 billion system, defying warnings that such military cooperation was incompatible with NATO and would let Russia improve its targeting of Western planes.

“The United States made clear to Turkey at the highest levels and on numerous occasions that its purchase of the S-400 system would endanger the security of US military technology and personnel and provide substantial funds to Russia’s defense sector, as well as Russian access to the Turkish armed forces and defense industry,” Pompeo said.

“Turkey nevertheless decided to move ahead with the procurement and testing of the S-400, despite the availability of alternative, NATO-interoperable systems to meet its defense requirements.”

The United States has already evicted Turkey from joint efforts in developing the F-35 fighter jet.

Rebukes By Turkey, Russia

The Turkish foreign ministry called the decision “unfair” and urged the United States to reconsider.

“Turkey stands ready to address this issue through dialogue and diplomacy in conformity with the spirit of alliance,” the Turkish foreign ministry said.

Russian Foreign Minister Sergei Lavrov called the sanctions “another manifestation of an arrogant attitude towards international law” by the US, which pursues its own “illegitimate, unilateral coercive measures.”

However, the United States said it was left with no choice. In October, Turkey began testing the S-400 after US officials said they would walk back their threatened sanctions if the ally essentially kept the system “in the box.”

“We engaged in months and months of diplomacy with the Turkish government at every level to help Turkey find an off-ramp,” senior State Department official Matthew Palmer told reporters.

“Imposing sanctions on a NATO ally is not something we take lightly.”

However, the Trump administration held off on more severe options presented for consideration, including sanctions that would hit the financial system or Erdogan personally.

While angry over the S-400s, experts say that the United States understands that Turkey’s relationship with Russia is complicated, with the two powers on opposing sides in conflicts in Syria and Libya and between Armenia and Azerbaijan.

The State Department announced the move only after Congress overwhelmingly approved a defense package mandating sanctions on Turkey over the S-400, giving the administration less wiggle room.

European Union leaders last week also agreed to draw up a list of Turkish targets for sanctions after Ankara’s assertive maritime moves in disputes with members Greece and Cyprus.

Erdogan has been “basking in glory” of late. The big question is whether Trump will re-admit Turkey to the F-35 program despite having the Russian S-400 systems.