The image of al-Qaida, haughtily promoted from within and resignedly conceded from without, has been that the terrorist organization and its murderous agents are too cunning, too disciplined, too just plain smart to be stopped. Against that, the way Khalid Sheik Mohammed, the architect of the Sept. 11 attacks, was stopped in Pakistan Saturday stands in welcome contrast.

He was arrested not after a heroic shootout, but in his sleep. His “perp walk” photo is not of a defiant soldier, but of a bleary-eyed guy in need of a shower, a shave and a clean shirt. More importantly, his arrest was not the result of high-tech magic or sheer luck, but of dogged police work. His lair in Rawalpindi was found because an underling arrested two weeks earlier ratted him out. If nothing else, the legend of al-Qaida’s super-omerta has been exposed as myth.

This is a victory in the war on terrorism – the question, of course, is how big a victory. By any fair reckoning, the capture of al-Qaida’s operations chief, the head planner of attacks, the person who gives the “go” signal for their launch, is very big. The clutter seized in his hideout – papers and computer disks – may lead to the exposure and breakup of terrorist cells all over the world, perhaps even to the capture of Osama bin Laden and other senior al-Qaida leaders. It is believed that this arrest will halt an al-Qaida-Taliban offensive planned against the Afghan government this spring; some of the cell phone and Internet “chatter” that led to the recent Code Orange alert has been traced to Mr. Mohammed.

The removal from active duty of this particular terrorist and the evidence it provides that U.S. intelligence and law enforcement agencies are getting and using effective help from Pakistani authorities are cause for celebration and encouragement. It is not, as one member of Congress boasted, the equivalent of the 1944 liberation of Paris, but it is a retort to the claim that the Bush administration is neglecting the ongoing war on terrorism in pursuit of a future war on Iraq.

After the immediate importance of thwarting planned attacks in this country and Afghanistan, the great benefit of this arrest is that it may refocus attention – of the public, Congress, the administration and the governments of other nations – on those terrorists at large for whom the furor concerning Iraq has provided some cover. Among those still at large are, of course, bin Laden, two-thirds of al-Qaida’s senior leaders and hundreds of operatives. It is believed many are hiding in the rugged frontier regions along the Afghan-Pakistan border; the dangerous work of tracking them down has been shown to be beyond the capabilities of the Pakistani military; it requires a concerted international effort. Now, with this encouraging victory, the information it will yield and the damage it has done to the al-Qaida image, is the time to begin.