U.S. President Donald Trump said on Monday evening that effective immediately, any country that does business with the Iranian regime will be subject to a 25% tariff “on any and all business being done with the United States of America.”

“This order is final and conclusive,” Trump said.

Nikki Haley, a former U.S. ambassador to the United Nations and former South Carolina governor, wrote that it was a “strong move by President Trump.”