WASHINGTON — (CNN) The State Department is warning Americans about the risk of potential terrorist attacks throughout Europe as law enforcement waits on heightened alert for possible ISIS-inspired attacks.

The department on Tuesday issued a travel alert for the continent.

There isn’t a new, specific threat, but the warning comes ahead of big events this summer with large crowds.

Venues in France will host the European Soccer Championship beginning on June 10, and the Catholic Church’s World Youth Day will be held in Krakow, Poland.

Both events are expected to draw massive crowds, and concerns are particularly high over the soccer tournament.

“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,” the new State Department alert reads.

The travel alert, which expires on August 31, follows increased worry after two large terrorist attacks in Europe, first in Paris and then two months ago in Brussels, Belgium.

The United States has for some time warned U.S. citizens to stay vigilant in crowded settings abroad. But U.S. intelligence and counterterrorism officials believe Europe is in for a summer similar to last year’s in the United States.

The FBI increased 24/7 surveillance of jihadist suspects and made more than a dozen arrests. In some cases, suspects were arrested on non-terror related charges simply to get them off the streets and out of fear it wasn’t safe to wait to gather terror-related evidence.

A French intelligence official told CNN recently that authorities don’t believe they’ve arrested all members of an extended cell behind the recent attacks in Paris and Brussels.

While they know more about the cell and have identified more people serving as supporting role, the threat hasn’t waned, the official said.