The U.S. State Department recently updated its travel warning for several Western European countries, cautioning about potential terrorist attacks.

Federal officials routinely issue updates or travel advisories for other countries. The advisories range from “Level 1: Exercise Normal Precautions” up to “Level 4: Do Not Travel.”

Earlier this month, the State Department raised its warning level for the United Kingdom and Italy to “Level 2: Exercise Increased Caution.” It did the same for Denmark on Tuesday.

The reason for the increased alert in all three cases was a concern over terrorism.

“Terrorists may attack with little or no warning, targeting tourist locations, transportation hubs, markets/shopping malls, local government facilities, hotels, clubs, restaurants, places of worship, parks, major sporting and cultural events, educational institutions, airports, and other public areas,” the warning said in all three instances.

Travelers are advised to be aware of their surroundings at all times, follow local authorities’ instructions, monitor breaking news, and adjust plans based on any new information.

The State Department added that there is a risk of “isolated violence” in the U.K. “by dissident groups in Northern Ireland, focused primarily on police and military targets.”

Other countries that also received a Level 2 advisory include:

• Lesotho
• Sri Lanka
• Jordan
• Saudi Arabia
• Bahrain
• Tanzania

A variety of alerts was also issued for Mexico, warning about violent crime and kidnapping in several areas.