President Donald Trump said on Monday the United States was in talks with a “more reasonable regime” to end the war in Iran but repeated his warning to Tehran to open the Strait of Hormuz or risk U.S attacks on its oil wells and power plants.

“Great progress has been made but, if for any reason a deal is not shortly reached, which it probably will be, and if the Hormuz Strait is not immediately ‘Open for Business,’ we will conclude our lovely ‘stay’ in Iran by blowing up and completely obliterating all of their Electric Generating Plants, Oil Wells and Kharg Island,” Trump wrote in a social media post.

Trump also threatened to attack the desalination plants that supply clean water in Iran.

The U.S. president said last week he would pause attacks on Iran’s energy plants for 10 days, which would be until April 6, U.S. time.

While Trump has said the U.S. and Iran are making progress in talks, he has also been sending more U.S. ​troops to the region, leading Iran’s parliament speaker to accuse Washington of sending messages about possible negotiations while planning a ground invasion, prompting more defiance ⁠from Tehran.

Iranian leaders have denied being in direct talks with the U.S.

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(Reporting by Susan Heavey and Doina Chiacu; Editing by Alex Richardson and Kevin Liffey)