Dhaka, June 1 -- With the summer travel season fast approaching, the United States has issued updated travel advisories warning of the risk of terrorist violence in several popular European destinations.

The U.S. State Department's alerts cover the five European countries that typically see the highest number of American visitors: the United Kingdom, Germany, France, the Netherlands, and Italy.

Spain-experiencing a sharp rise in popularity among U.S. tourists-has also been included, alongside Belgium, Denmark, Sweden, and several other nations across the continent.

The advisories are based on the State Department's four-tier travel alert system, which ranges from Level 1, "Exercise Normal Precautions," to Level 4, "Do Not Travel." Leve...