Brits Fear Irish Terrorists Will Attack Royal Wedding

British authorities are on high alert, afraid that the wedding of Prince Williams and Kate Middleton represents an all-too-juicy target for the so-called "Real IRA," or another Irish militant group. Though there have been no specific threats, security officials tell ABC News that they have “concrete intelligence” that the Real IRA is trying to expand its operations to London, and that MI5 is now more focused on them than on al-Qaeda.

“It is fair to assume that people are worried about an attack on the mainland,” says Northern Ireland’s chief of policed service. “There is a massive effort by the intelligence services to track these people down.” (More Real IRA stories.)