The US State Department has issued a travel advisory for Europe, based on information suggesting an imminent Al-Qaeda attack. The advisory implores all Americans in Europe to be aware of their surroundings and take adequate safety precautions when travelling.

Canada has yet to post any similar warnings on their own web site.

The advisory is not meant to tell Americans not to travel, but rather be suspicious while travelling across the continent. Japan also issued similar warnings to its citizens after intelligence information was shared between Western allies. They advise that they are working closely with European governments to prevent terrorist attacks from Al-Qaeda.

A senior administration official who spoke on condition of anonymity said Obama met with members of his national security team Friday night and Saturday morning and received another briefing Sunday morning. The official said European allies are "all in sync" with the United States, "both in terms of our assessment of the threat as well as our shared conviction that governments have an obligation to keep their citizens informed of terrorist threats."

A former State Department counter-terrorism expert told CNN, "The State Department is historically extremely cautious about these things." He stated they do not want to be blamed for not warning Americans if they have information about possible attacks, but the alert is less sever than more formal travel warnings issued for previous threats.

Kennedy said he could not recall the last time a travel alert was issued for an entire continent due to security reasons. Earlier this week officials were looking at intelligence which hinted at the possibility of Mumbai-style attacks across European cities. The Mumbai attacks took place in November 2008 when armed terrorists stormed two prominent hotels, a historic train station and a Jewish cultural center.

The Los Angeles Times have reported the intelligence warning of the attack came from the interrogation of a German-Pakistani man who is being held at a US base in Afghanistan. All across Europe the governments have been alerting the public of the possibility of imminent terrorist attacks.

Germany's interior ministry said in a statement that the warning for Americans comes in light of recent threats and that Berlin was informed by the U.S. of the decision to issue the alert.

A spokeswoman for Spain's Interior Ministry told CNN that the country will remain at Level 2 alert, which indicates a "high, probable risk" of a terror attack.