President Donald Trump on Tuesday ordered a review of the U.S. visa program for bringing high-skilled foreign workers into the country, putting technology firms and the outsourcing companies that serve them on notice that possible changes may be ahead.Seeking to carry out a campaign pledge to put “America First,” Trump signed an executive order on the H-1B visa program. It was vague on many fronts, and did not change existing rules, but one objective, said Trump aides, is to modify or replace the current lottery for H-1B visas with a merit-based system that would restrict the visas to highly skilled workers. Indian nationals are the largest group of H-1B recipients annually.Such a change could affect companies, such as Tata Consultancy Services Ltd, Cognizant Tech Solutions Corp and Infosys Ltd, that connect U.S. technology companies with thousands of foreign engineers and programmers. None responded to requests for comment.Trump announced the order and made remarks at a visit to the headquarters of Snap-On Inc, a tool maker in Wisconsin.In addition to addressing the visas issue, he also ordered a review of government procurement rules favoring American companies to see if they are actually benefiting, especially the U.S. steel industry.”With this action, we are sending a powerful signal to the world: We’re going to defend our workers, protect our jobs and finally put America first,” Trump said.Trump was a businessman before he was elected president last year, and his companies have been criticized for using visa programs to fill positions at Trump properties with foreign workers. Trump-branded products are also made overseas.