The U.S. Defense Department has banned U.S. troops and employees from traveling in their free time within 50 kilometers of Paris, following the terrorist attacks in the French capital on Friday night.

The ban was put in place late Sunday by U.S. European Command. It applies to all military personnel, civilian employees, contractors and family members who are sponsored by a specific military command. Anyone who wants to travel to the area on official business or for emergency reasons must obtain approval from a general officer or other senior official in their chain of command.

“This is a precautionary measure to keep our personnel and families safe in light of the recent attacks,” a European Command announcement said. “This is also an effort to help minimize tourist traffic at the borders in France, and in particularly, in Paris as the French authorities continue their investigation.”

Exceptions are granted for U.S. military assigned to diplomatic posts in France, such as the U.S. Marines who guard the embassy in Paris. Individual who have commercial airline connections in France and who are not leaving the airport also are exempt.

Navy Capt. Jeff Davis, a Pentagon spokesman, referred questions about the travel ban to European Command on Monday. He said it will be in effect until further notice.