No specific threats have been made at this time, but the State Department wants travelers to remain vigilant.

Brussels skyline
Credit: Getty Images

Yesterday, U.S. State Department officials updated a travel alert for all of Europe, warning that American tourists should be on high alert for potential terrorist attacks this summer. The wide-ranging alert was originally put forward in March, after the Brussels attacks.

Now the alert—which is vague at best and not particularly dire—urges travelers to be particularly mindful of the risk in attending major events during the summer months, including the European Soccer Championship and the Tour de France.

Later in the season, Poland will host the Catholic Church’s World Youth Day. As many as 2.5 million visitors could descend on Poland between July 26 and 31, straining the local infrastructure and security forces.

While tourism to certain cities, such as Istanbul and Brussels, has taken a dramatic dip after recent attacks, American visits to Europe are still on the rise. This summer, Allianz Global Assistance projects a rise in tourism by a modest 9.3 percent.

With so many Americans abroad, the State Department encouraged tourists to “exercise vigilance” when in public spaces like restaurants, major sites, commercial centers, and transportation hubs: all of which could easily be targeted by terrorist groups during the busy summer season.

For more information about what to do when the State Department issues an alert—and how to stay safe if you’re traveling anyway—click here.

Melanie Lieberman is the Assistant Digital Editor at Travel + Leisure. Follow her on Twitter and Instagram at @melanietaryn.