Just a few days ago, some European capitols were complaining about Washington's publicizing the possibility of a Mumbai-style terror attack in Europe.

Now both Britain and France are warning their citizens that an attack is "highly likely:"

The warning came after the British government raised its terror alert level for travellers to France, along with Germany, from "general" to "high", while leaving its domestic threat level unchanged at "severe", where it has been since September 22.

"The French saying an attack is highly likely is true because that is where our threat level is," said a spokeswoman for London's Counter Terrorism Command.

On Sunday the UK and the US both warned of an increased risk of terrorist attacks in Europe, with security officials saying al Qaeda might seek to launch attacks emulating the 2008 Mumbai attacks by Pakistan-based gunmen that killed 166 people.

France has been buffeted by a series of alarming comments from top officials over the past two weeks about the imminent threat of a major terrorist strike. The Eiffel Tower in Paris was twice evacuated after what turned out to be false bomb scares. French officials have pointed the finger at al-Qaida's North African wing, al-Qaeda in Islamic Maghreb, which is currently holding five French nationals hostage in Niger. 

These warnings appear to be the most serious threat of mass casualty attacks in many years. And just because we know about them doesn't mean they've been stopped. If there is some sort of countdown underway, we will have to be extremely lucky to avoid what appears to be possibly several different commando type attacks, any one of which could lead to many deaths.