President Donald Trump ordered his administration Tuesday to begin blocking Canadian products from a federal contracting program worth more than $50 billion annually, opening another front in the rapidly escalating feud between the United States and Canada.

Trump said in a Truth Social post that he directed the General Services Administration, working with the U.S. trade representative, to “take all necessary steps” to remove Canadian products from the agency’s multiple awards schedules, which allow federal agencies to purchase millions of commercial products and services from preapproved vendors, unless Canada provides what he called “full and fair reciprocity” for American companies.