U.S. President-elect Donald Trump sternly warned American businesses again Sunday that if they move their operations overseas they would face a 35 percent tax if they then try to sell their products back in the United States.

In a series of Twitter comments, Trump said he plans to “substantially reduce” taxes and regulations on businesses. But he said that any company that “fires its employees, builds a new factory or plant” in another country “and then thinks it will sell its product back into the U.S. without retribution or consequence, is wrong!”