BBC News | September 11: One year on

Morocco emerged as a major source of concern when the police there announced the arrest of three Saudis, their Moroccan wives and a Moroccan man who, it was said, had planned an attack on Western warships in the Strait of Gibraltar, probably British or American.

Their plan was allegedly to load a small fast boat with explosives and ram it into a ship just as USS Cole had been rammed in Yemen in October 2000. It is thought that they had escaped from Afghanistan after the American bombing started.

The pattern of their operations gives a hint as to what al-Qaeda did next � it split up into small groups, using local knowledge to try to develop attacks. By making the arrests public, the Moroccan King Mohammed Vl has signalled that he will not tolerate al-Qaeda activity.