Iranian forces reportedly shot down an American MQ-9 Reaper drone in the hours before Thursday's attack on two oil tankers near the Strait of Hormuz, a U.S. official tells CNN. Why it matters: Heightened tensions and hawkish American rhetoric in the wake of Thursday's incident have brought back recently reduced fears that the U.S. could be on course for war with Iran. Secretary of State Mike Pompeo and President Trump have accused Iran of being responsible for the oil tanker attacks based on U.S. intelligence that has not been made public.The administration released a video on Friday purporting to show Iran’s Revolutionary Guard removing a mine from one of the oil tankers after the attack. "It’s probably got essentially Iran written all over it," Trump said in a Fox & Friends interview, referring to the video.Details: Before the U.S. drone was shot into the water by surface-to-air missiles, it "observed Iranian vessels closing in on the tankers," the U.S. official told CNN. The official did not say if the drone "saw the boats conducting an actual attack." They also claimed another U.S. Reaper drone was shot into the Red Sea on Wednesday by what is believed to be a Houthi-fired Iranian missile.The other side: The Iranian mission to the U.N. dismissed accusations of orchestrating the oil tanker attack as "unfounded" on Thursday and called for an immediate dialogue to reduce pressure and prevent "the reckless and dangerous policies and practices of the U.S."Iran's president also said Saturday the country would continue to scale back its compliance with provisions of the 2015 nuclear deal until other parties to the agreement show "positive signs," Reuters reports.Go deeper: Pompeo blames Iran for attacks on oil tankers