President Trump’s team is tightening enforcement of the rules governing a visa program for high-skilled workers, and changing policies to protect lower-skilled workers from foreign competition.

A new policy announced Monday would allow U.S. Citizenship and Immigration Services agents to prioritize companies for site visits if they seem likely to engage in “visa fraud and abuse.”

USCIS agents plan to make unannounced visits to companies that trigger visa fraud red flags, such as having “a high ratio of H-1B workers as compared to U.S. workers, as defined by statute,” according to the bulletin. Companies for which basic business information cannot be validated will also be targeted.

The agency is also establishing an email that people can use to alert USCIS when they think their employer is gaming the high-skilled visa system. “Employers who abuse the H-1B visa program negatively affect U.S. workers, decreasing wages and job opportunities as they import more foreign workers,” according to USCIS. “Information submitted to the email address will be used for investigations and referrals to law enforcement agencies for potential prosecution.”