Europe has been of a high state of terror alert since the Charlie Hebdo attacks in January 2015, the Paris attacks on November 13, 2015 and the March attacks in Brussels. Now the US State Department has issued a travel notice warning of potential attacks on major events between June and the end of August.
The State Department's statement said:
"We are alerting US citizens to the risk of potential terrorist attacks throughout Europe, targeting major events, tourist sites, restaurants, commercial centers 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. This Travel Alert expires August 31, 2016."
France will host the 2016 UEFA European Championship from June 10 to July 10.
France has extended its state of emergency through July 26 to cover the period of the soccer championship, as well as the Tour de France cycling race which will be held from July 2- 24.
Daesh Terror Threat
The Catholic Church's World Youth Day event is expected to draw up to 2.5 million visitors to Krakow, Poland, between July 26 and July 31.
"Poland will impose border controls at all of its national borders from July 4 to August 2, and visitors to Poland during this period should be prepared to show their passport and undergo stricter security screening throughout Poland," the statement said.
Rob Wainwright, director of the EU's law enforcement agency Europol, said the threat from Daesh, also known as ISIL, is "more widespread network than we first feared".
"It threatens not just France and Belgium but a number of European countries at the same time. It is difficult to know how many of those are on active duty in preparing to launch attacks in Europe but we are concerned about a community of 5,000 suspects that have been radicalized in Europe, that have traveled to Syria and Iraq for conflict experience, some of whom, not all, have since come back to Europe."
"Some of those will be among those that are taking part in what is clearly a new strategy that so-called Islamic State has launched now in the West to take us on in a more aggressive way, to use teams of well-trained, well-planned terrorists to carry out multiple attacks aimed at mass casualties," Wainwright said.