The United Kingdom updated its advice for travel to the United States on Thursday, warning of harsh consequences for British passport holders who violate U.S. immigration laws. The notice comes just a day after Germany updated its travel advice after three of its citizens were detained trying to enter the U.

The Trump administration’s hard-line policies have prompted Germany and the U.K. to issue travel advisories for visiting the U.S.

Two major European countries are warning citizens about travel to the U.S. following high-profile cases in which American federal immigration authorities detained tourists and U.S. green cardholders trying to enter the country.