The horrifying bombings in London yesterday remind us that terrorists and their tools remain among us all.

After Sept. 11, we began to become accustomed to the idea that the "war" on terror was being exported to the home territory of those who use this terrible weapon.

Indeed, that is one of the basic arguments behind our invasion of Afghanistan and then Iraq.

"We can fight them there or we can fight them here," goes the argument. "It is better to fight them on their home turf."

Well, the London attacks reinforce the point that there is no "home turf" for terrorists. They operate when and where they wish.

The London attacks also remind us that the enemy is not "terror." Terrorism, after all, is simply a weapon used by all manner of people, from Islamic jihadists, to fighters seeking to win independence from what they see as an uncaring central government, to garden-variety crackpots.

So the lesson is clear: One cannot identify any particular group, go after its members and describe them as the object of a war on "terror." Their thinking and motivation are as varied as their methods.

So too must be our response. Battling terror requires more than military might. It calls for keen intelligence work, canny diplomacy and unrelenting attention to security.

London's immediate reaction to the attacks was admirable. Prime Minister Tony Blair was resolute, the people remained calm, and emergency procedures in place worked relatively well.

Going forward, security will be tightened in London and, indeed, around the world. Police investigations are already well under way, and we hope they will be as successful as the remarkable investigations that followed 9/11, the bombings in Madrid and elsewhere.

We cannot, and will not, allow the terrorists to shake our resolve. They cannot prevail as long as people of good will and strong hearts refuse to let them.