The Sept. 11, 2001, al-Qaida attacks that killed nearly 3,000 Americans were perhaps the highest-profile terrorist attacks by any radical Muslim group in recent years.

But they were by no means an isolated incident. In the years since, there have been countless militant Islamic terrorist attacks around the world.

Just in recent months, for instance, a radical sect of Islam burst into a town hall meeting in Nigeria and used assault rifles to slaughter at least 20 Christians as they were peacefully discussing some funeral arrangements. Other attacks by the sect have taken place the past few weeks.

Meanwhile, in France, a radical Muslim gunned down three Jewish children and a rabbi at a Jewish school. He also killed three French paratroopers. The man said he wanted to avenge Palestinian children, but could he truly have thought he would gain sympathy for his cause by gunning down defenseless youngsters and a rabbi?

Tragically, no country -- whether it be Nigeria, France or the United States -- can perfectly predict and therefore always head off the vicious actions of terrorists.

But as these violent acts remind us, radical Islam poses a serious threat to civilized society. And as such, all civilized nations should remain vigilant against that threat whenever it may surface.