President-elect Donald Trump warned American businesses against any plan of exporting their jobs to Mexico.

“The U.S. is going to substantially reduce taxes and regulations on businesses, but any business that leaves our country for another country, fires its employees, builds a new factory or plant in the other country, and then thinks it will sell its product back into the U.S. without retribution or consequence, is WRONG!” he wrote on Twitter early Sunday morning.

Trump warned that he would put a 35 percent tax on businesses trying to move their factories over the border and sell their products back to Americans in the United States.

“This tax will make leaving financially difficult, but these companies are able to move between all 50 states, with no tax or tariff being charged,” Trump said. “Please be forewarned prior to making a very expensive mistake! THE UNITED STATES IS OPEN FOR BUSINESS.”