Why has this new group, the Islamic State of Iraq and Syria (ISIS or just IS), which outstrips even al-Qaida in brutality, suddenly thrust its acts of horror into our living rooms?

In 1991, the United States led an international force that routed Iraqi forces who had invaded Kuwait. We fought that war to maintain world oil supplies. Saddam was threatening two major oil suppliers, Kuwait and Saudi Arabia.

Some cautioned that oil should not pull us into a shooting war in the Middle East and that a war fought for oil companies was immoral. At least the U.S. was wise enough not to advance into Iraq but stopped with the liberation of Kuwait, a country that asked for our help.

We should at least have understood the consequences. Middle Eastern violence would not stop with our defeat of Saddam, either in that war or the later one. Extremist factions in the Middle East resented interference by Western powers. They wanted Saddam defeated by Islamists and the restoration of Islamist empires of the past.

All are related to the humiliation of Islamist nations since the nineteenth century and the carving of spheres of influence in the Middle East by Western powers. Forces of secularization are clashing with centuries-old cultures. The accumulation of wealth by corrupt leaders also plays a part.

These issues were behind later terrorist incidents, including the attacks on our own country in 2001. They are a chief reason for the IS faction now.