Parties who had existing agendas for going to go to war against Iraq (balance of power, oil, etc.), were saying that it would take a "Pearl Harbor type event" to convince the US to to wage such a war. Then, conveniently, 9/11 happened, and the US went to war against Iraq.

Now, we have people saying it will take major terrorist attacks on Europe to get them to help out with a war against Iran.

Based on that, I think we can safely assume that the people with long-standing agendas for going to war against Iran (balance of power, oil, etc.) will now arrange for such terrorist attacks to conveniently take place in Europe.