U.S. Secretary of State Mike Pompeo called Russia's delivery of the S-300 surface-to-air missile system to Syria a "serious escalation" on Wednesday, Haaretz reported.

Pompeo's statement came after the Russian Defense Ministry published a video Tuesday night of the systems' delivery. Russian crewmembers appear to be unloading of the launcher, the radar and the commanding control vehicle.

Pompeo also announced that the U.S. is canceling a 1955 treaty with Iran establishing economic relations and consular rights between the two nations.

The move follows a ruling by the United Nations’ highest court ordering the United States to lift sanctions on Iran that affect imports of humanitarian goods.

Pompeo told reporters Wednesday that the termination of the treaty was decades overdue. He said that Iran was abusing the International Court of Justice for political and propaganda purposes.

He said Iran’s claims under the treaty were “absurd.”