The US has warned its fans that terrorists may target Euro 2016.
The Department of State singled out the competition in France as it published updated travel information for Americans.
France will host the tournament from June 10 to July 10, with hundreds of thousands of fans set to flock to the country from around Europe to follow the matches.
The alert adds: "European authorities continue to take steps to assure public safety and disrupt terrorist plots."
"We work closely with our allies and will continue to share information with our European partners that will help identify and counter terrorist threats", they said.
Authorities in France have extended a state of emergency until the end of the event, as well as the Tour de France cycling race, which will be held from July 2 to July 24.
Last week UK police said up to 500,000 British fans, around half of whom do not have tickets, are expected to travel to France for the tournament.