The British government also on Sunday raised the threat of terrorism for its nationals in France and Germany to “high” from “general” in a travel advice update.
“The travel advice for France and Germany has been updated. Like other large European countries, they have a high threat of terrorism, which is reflected in our updated travel advice,” a spokesman for the Foreign and Commonwealth Office (FCO) said.
The US State Department travel alert said public transportation systems and other tourism-related facilities could be targets, noting that past attacks had struck subway, rail and airline systems as well as maritime services.
“The State Department alerts US citizens to the potential for terrorist attacks in Europe,” it said in an advisory on its website. The advisory said “current information suggests” Al-Qaeda and affiliated groups continue to plan such attacks.
“European governments have taken action to guard against a terrorist attack and some have spoken publicly about the heightened threat conditions,” the department said.
The potential threat was outlined last week in media reports, subsequently confirmed by European officials, that Europe could be the target of such attacks.
A US official said the State Department, which regularly issues travel alerts to US citizens planning to go abroad, was catching up with last week's revelations rather than heralding a new threat.
Western intelligence sources said last week militants in hideouts in northwestern Pakistan were plotting coordinated attacks on European cities, the plans apparently surviving setbacks from a recent surge in drone strikes. The plot involved Al-Qaeda and allied militants, possibly including European citizens or residents, the sources said.
British media said intelligence agencies disrupted plans for multiple attacks on European cities by a group thought linked to Al-Qaeda, with militants planning simultaneous strikes in London, as well as in cities in France and Germany.
At the time, Germany's Interior Ministry said it knew of information pointing to planned attacks by al Qaeda in the United States and Europe but that Germany's security threat level had not changed.
The last successful large-scale militant attack in the West was the 2005 bombings on London's transport system, which killed 52 people.
In its alert, the State Department said Americans should take “every precaution to be aware of their surroundings” and should take appropriate safety measures to protect themselves when traveling.
The department said the United States continues to work closely with European nations to combat “the threat from international terrorism” and that information is routinely shared to defend against potential attacks.
