IT WILL BE a central theme of the next four years, affecting everyone from firefighters to travelers to chief executives. Yet the presidential debate on homeland security has been shockingly anemic. In part, this is because the national debate on homeland security is shockingly anemic too. Despite the creation of a vast new Department of Homeland Security and despite the billions of dollars the government has poured into homeland security over the last three years, there has been little hard discussion in Congress, in the media or elsewhere about just what the nation's long-term homeland security priorities should be. It is possible, after all, to spend unlimited amounts protecting infinite numbers of potential targets: nuclear and chemical plants, water treatment plants, airports, train stations, ports, cargo ships, border outposts, the nation's computer and telecommunications networks, the public health system, and biological laboratories. Yet, few politicians have dared to stand up and declare that some targets are more important than others, that some risks are less frightening than others, and that some homeland security investments are not worth making at all.

Certainly the Bush administration has not done so. Although the White House did, under pressure, endorse the creation of a new Department of Homeland Security, and although the last three years have seen the creation of a new airline security system and the implementation of some new border technologies, the task of setting meaningful priorities is still incomplete. Too much homeland security money has been distributed according to the whims of congressmen with powerful fire or police unions in their districts. It's probably safe to say that airline security has been over-emphasized while procurement of vaccines and development of antidotes to biological and radiological attacks is moving far too slowly. Despite the passage of the president's much-vaunted Projected Bioshield legislation, it is still very difficult for private drug companies to work with the government, and valuable research has been delayed as a result. On the campaign trail, the president has glossed over all of these nuances, using platitudes like "We're doing everything we can to protect our borders and ports" and trumpeting the creation of DHS as if that were all that needed to be done.

Sen. John F. Kerry has not, so far, contributed much to the urgent need for a debate about prioritization either. In an effort to score points, he has several times pointed out that "95 percent" of containers coming into this country have not been inspected. But has he calculated the enormous cost of inspecting every con- tainer -- not to mention the damage to commerce? Is he really certain that cargo inspection is the best way to invest the nation's homeland security money? The provision of fire trucks and other emergency equipment to every small town in America may sound nice in a stump speech, but it's got nothing to do with real homeland security preparation. To its credit, his campaign has produced a sophisticated analysis of the bioterrorism threat, but Mr. Kerry himself has hardly touched on this. Given the opportunity in the third debate to talk about the lack of a vaccine infrastructure, a critical bioterrorism preparedness issue, he ducked the question and spoke about unrelated health care reforms instead. Both candidates have approached the vital homeland security debate with disappointing simple-mindedness and apathy.

This is one in a series of editorials comparing the records and programs of the presidential candidates on important issues. Others can be found at www.washingtonpost.com/opinion.