It appears that the western democracies have decided that the best way to prevent terrorist attacks is to make the threat public:

Saudi Arabia has warned France it is the target of an imminent al-Qaeda attack, French Interior Minister Brice Hortefeux has said.

He said Saudi intelligence agencies spoke of a threat to Europe, and "France in particular", from al-Qaeda in the Arabian Peninsula.

France is already on high alert following warnings of possible attacks aimed at France, Germany and the UK.

The Eiffel Tower was evacuated twice in September over security alerts.

"I can tell you - and it's not information that's been made public yet - that even a few hours, a few days ago, [we received] a new message, from the Saudi [intelligence] services, indicating to us that Al-Qaeda in the Arabian Peninsula was certainly active, or expecting to be active," Mr Hortefeux said in a joint radio and television interview.

He said the threat concerned "the European continent and France in particular".

Mr Hortefeux gave little detail about the information the Saudis had provided, but said the threat was real.

Won't these governments be accused of "scaremongering" and using the warning to gin up political support? Some in France are already questioning the tactic of publicizing the threats. But in the end, a warned citizenry is a safer citizenry and if the tactic works, I doubt the governments in Europe or here will mind the criticism very much.