State Department building
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The U.S. State Department on Monday issued a travel alert for Europe, warning U.S. citizens to be aware of a continued threat of terrorist attacks throughout the continent.

In the alert, quoted by Reuters, the State Department cited recent incidents in France, Russia, Sweden and the United Kingdom. It added that the Islamic State (ISIS) and Al-Qaeda terrorist groups "have the ability to plan and execute terrorist attacks in Europe."

The U.S. has issued travel warnings to Europe in the past. The State Department's previous travel alert for Europe, issued ahead of the winter holiday season, expired in February.

A State Department official told Reuters that Monday's alert was not prompted by a specific threat, but rather recognition of the continuing risk of attacks especially ahead of the summer holidays. The alert expires on September 1.

Malls, government facilities, hotels, clubs, restaurants, places of worship, parks, airports and other locations are all possible targets for attacks, the State Department's alert said.

Last week, police in London arrested a terrorist suspected of planning an attack in the city. It was later revealed that the terrorist was on the Mavi Marmara ship, which was raided by Israeli soldiers in 2010 while trying to violate Israel’s naval blockade of Gaza.

Two weeks ago, a French policeman was killed and two others were wounded in a shooting attack on the Champs-Elysees in Paris. The attack was claimed by ISIS.