After months of speculation about changes to U.S. temporary worker visa programs, President Donald Trump signed an executive order on Tuesday that aims to retool the H-1B program from a lottery to a merit-based system, as part of a “Buy American, Hire American” initiative also overhauling federal procurement procedures.

Trump’s order begins a 220-day review process in which federal agencies will review and propose changes to the H-1B program that would restrict the program to only workers with the most advanced skills.