"I will be announcing my decision on the Iran Deal tomorrow from the White House at 2:00 pm," Trump said in a tweet.
Trump has until Saturday to decide whether to renew a 120-day waiver of sanctions that Congress previously imposed on Iran. If he does not renew the waiver, it would signal to U.S. allies and Iran that the U.S. wants to pull out of the nuclear deal negotiated under President Barack Obama.
The agreement, to which the U.S., U.K., Russia, France, China and Germany are parties, lifted sanctions on Iran in return for limitations on that country's nuclear program.
Before Trump's tweet about his upcoming announcement, some Republican lawmakers — including longtime critics of the deal — had been urging him to stick with the agreement and try to change it, not withdraw completely.