The energy industry is not a new target. McCredie recalled that significant changes in security followed terror attacks in Saudi Arabia, including a 2004 hostage-taking incident at oil industry compounds at Khobar which ended in the deaths of 22 people."There have been all sorts of attacks in other places, Yemen, Syria, Iraq. These attacks are not unusual. What's unusual about this one is it was a big surprise. It shouldn't have been," McCredie said. Al-Qaida in the Islamic Maghreb "had been making these threats for a long time. No one thought they had the capacity." But, he said there are limits to what even extra security forces could accomplish in the battle against terrorists. "They are mobile, it's a huge vast area, very, very difficult to police, and difficult to keep up surveillance, so a small number of people can have the element of surprise," McCredie said. "Security forces can't patrol the whole area." ___ AP reporters Gregory Katz, Jill Lawless and Cassandra Vinograd in London and Greg Keller in Paris contributed to this report.