PRESIDENT BUSH boasted again yesterday that his administration is "on the offensive" against terrorism and is "chasing down these killers overseas so we don't have to face them here at home." At the Republican convention last week, he said his plan for Iraq was to "help new leaders . . . move toward elections and get on the path of stability and democracy as quickly as possible." Yet on the ground in Iraq stands a glaring contradiction to those statements: the Sunni cities of Fallujah, Ramadi and Samarra, where the United States has withdrawn its forces, allowing extremist movements and foreign terrorists to take over. These strongholds now pose a serious threat to U.S. forces, to Iraq's interim government and to the plan to hold national elections in January. Yet even as it contends with Shiite militants in southern Iraq and the slums of Baghdad, the U.S. military leadership has announced that it cannot eliminate these sanctuaries for Baathists and suicide bombers before December.

Is it only a coincidence that the Pentagon's timetable postpones a difficult and potentially costly showdown until after the U.S. presidential election? Defense Secretary Donald H. Rumsfeld and Air Force Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, argued at a news conference Tuesday that time is needed to lay the political and mili- tary groundwork. Iraqi forces, they say, are needed for any operation against the Sunni cities and would have to keep order afterward. Those national forces, they say, are not yet ready, even though the United States has been working to equip and train them for more than a year. The Iraqi government is meanwhile attempting to isolate the extremists politically: Prime Minister Ayad Allawi has been meeting with tribal leaders from Fallujah. U.S. forces are attempting to pressure the militants from a distance, through bombing strikes and artillery barrages.

There's no question that any military campaign against Fallujah or its neighbors will have to be carefully prepared; but there's no longer much question that it will be needed. The White House called off a Marine attack on Fallujah in April in the hope that a friendly local Iraqi force would step in and impose order, a decision that has proved to be a serious mistake. The hastily assembled local force never asserted control, and one of its commanders was recently captured and beheaded. A Taliban-like regime now rules Fallujah. Mr. Rumsfeld acknowledged that it is the base of Abu Musab Zarqawi, a Jordanian terrorist with ties to al Qaeda whose organization has carried out many of the suicide bombings in Baghdad. The Zarqawi organization, which aspires to operate far beyond Iraq, has made Fallujah the most open and dangerous sanctuary for Islamic terrorism since Osama bin Laden was driven from Afghanistan.

U.S. forces have already suffered painful losses in Iraq: The number of dead passed 1,000 this week, and no end to the violence is in sight. But the Bush administration, whose errors have done much to create this troubled situation, will only compound U.S. losses if it fails to act decisively against Iraq's Sunni extremists and the terrorists they harbor. The planned political transition, on which the chances for progress in Iraq depend, may well collapse if January's elections are derailed or discredited -- and elections cannot be held in the principal towns of western Iraq as they now stand. Even worse is the prospect of a terrorist organization conceded a haven in a country that the United States invaded to preempt just such a threat. The administration was wrong to allow that enemy base; it can ill afford to grant it three more months of grace.