Terrorists may target the Euro 2016 football tournament, the US government has warned.
The Department of State singled out the competition in France as it published updated travel information for Americans.
It said: "We are alerting US citizens to the risk of potential terrorist attacks throughout Europe, targeting major events, tourist sites, restaurants, commercial centres and transportation.
"The large number of tourists visiting Europe in the summer months will present greater targets for terrorists planning attacks in public locations, especially at large events."
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 state department alert, which expires on August 31, said: "Euro Cup stadiums, fan zones, and unaffiliated entertainment venues broadcasting the tournaments in France and across Europe represent potential targets for terrorists, as do other large-scale sporting events and public gathering places throughout Europe."
It sets out steps for US citizens to take including exercising vigilance in public places, as well as advising them to be prepared for additional security screening.
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."
Euro 2016 will take place amid an atmosphere of high alert and a huge security operation following atrocities in Paris and Brussels.
French authorities 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.
The travel alert also cites the Catholic Church's World Youth Day event in Krakow, Poland, which is expected to attract up to 2.5 million visitors.