In light of intelligence pointing to possible attacks by al-Qaeda in Europe (map, from bbcimg.co.uk), the US government has warned its citizens in an official travel advisory to be vigilant when travelling there.
The state department advised Americans to take care while in tourist areas, without specifying a country.
Security sources have warned of an al-Qaeda plan to send teams of gunmen to crowded places to kill civilians. They added that British, French and German cities were thought to be targets for the militants, in attacks that could be similar to the 2008 atrocities in Mumbai.
Last week intelligence details of the plot have been leaked to the US and British media, but officials said that the plan had not been stopped, and that an attack was not expected to be carried out imminently.
The state department alert said European governments had “taken action to guard against a terrorist attack”, but that “terrorists may elect to use a variety of means and weapons and target both official and private interests”.
“US citizens are reminded of the potential for terrorists to attack public transportation systems and other tourist infrastructure,” the alert sad.
“Terrorists have targeted and attacked subway and rail systems, as well as aviation and maritime services.”
If travelers fear the there is a risk of terror attacks and cancel their journeys, this alert could have negative consequences for European tourism.
However, the advisory is less serious than a travel warning.
Following the alert, UK Home Secretary Theresa May said Britain would continue to work with its allies to combat terrorism.
“I would urge the public to report any suspicious activity to the police in support of the efforts of our security services to discover, track and disrupt terrorist activity,” she said.
After news of the possible plot first came to light, US anti-terrorism officials were reported to have said that they believed al-Qaeda leaders, including Osama Bin Laden, were involved.
Even though no arrests have been made, European officials said several individuals were still under surveillance.
The suspects include British citizens of Pakistani origin and German citizens of Afghan origin.
Recent US drone raids in Pakistan reportedly targeted al-Qaeda militants linked to the plans.
US forces have carried out at least 25 drone strikes in the last month in Pakistan’s tribal areas, which is the highest monthly total for the past six years, US media reported.
Pakistani leaders have heavily criticised the frequent attacks by US drone aircraft, saying it killed innocent bystanders and infringed upon national sovereignty.
The attacks have been publicly condemned by Pakistan as violations of its sovereignty. Besides the attacks are unpopular among the Pakistani people.
However the Pakistani government is believed to assist in at least some of the missile attacks, even though the US does not publicly acknowledge the existence of the covert, CIA-run operation.
The UN has called for the US to end the CIA’s control over drone attacks.
Philip Alston, the special rapporteur on extrajudicial executions, said that the US spy agency does not provide enough transparency or accountability for the programme.
Alston added that the use of drone attacks risked creating a “Playstation” mentality towards killing, “because operators are based thousands of miles away from the battlefield, and undertake operations entirely through computer screens and remote audio-feed”.
The US has been pushing Pakistan to increase their search for the militants, who are believed to be hiding in a mountainous border region in the country.