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.

London’s Heathrow Airport has been brought to a complete standstill by a “significant power outage,” setting off waves of global travel chaos from one of the world’s busiest transit hubs.

The global travel industry was scrambling on Saturday to reroute passengers and fix battered airline schedules after a huge fire at an electrical substation serving London's Heathrow Airport forced closure of Europe's busiest air hub.

London’s primary airport, the main gateway for U.S. travelers to Europe, expects disruption for days as a result of a fire at an electrical substation. At least 1,300 flights were affected.