United States President Donald Trump has threatened to remove millions of people who entered the country illegally “as fast as they come in.” Trump wrote on Twitter that the U.S. Immigration and Customs Enforcement next week will “begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States.” The series of comments come as Trump prepares to officially start his re-election campaign Tuesday night. Limiting immigration was a central issue of Trump’s 2016 campaign. And he is expected to use the same issue in the upcoming 2020 campaign. The president also suggested that he will soon sign an agreement on migration with Guatemala. The agreement would make Guatemala the country where migrants fleeing El Salvador and Honduras would go to seek asylum instead of the U.S. or Mexico. Trump said the Central American country would become part of efforts to limit migration in the area with a tweet on Monday.