By Eugene Robinson - December 29, 2009

WASHINGTON -- Homeland Security chief Janet Napolitano's initial assessment of the Christmas Day airliner attack -- that "the system worked" -- doesn't quite match the absurdity of "Brownie, you're doing a heck of a job." But only because she quickly took it back.

A system that allows a man identified to U.S. officials as a potential threat -- by his own concerned father -- to board a flight from Amsterdam to Detroit with powerful explosives sewn into his underwear? That lets this man detonate his bomb as the plane prepares to land, igniting a potentially catastrophic fire? That depends on a young, athletic passenger to be seated nearby? That counts on this accidental hero to react quickly enough to thwart the terrorist's plans?

If that's how the system works, we need a new system.

Don't misunderstand. I'm not blaming the Obama administration for Umar Farouk Abdulmutallab's alleged terrorist attack, and it would be reprehensible for anyone to try to use the incident to score political points. The White House is guilty only of defensiveness in not immediately recognizing the obvious: We have a problem. Actually, we have two problems.

The first is that the Abdulmutallab incident reveals serious deficiencies in the "system" that Napolitano and others were so quick to defend. At this point, no one can doubt that civilian aviation remains a major target of al-Qaeda, affiliated groups and wannabe imitators. Most of us are under the impression that removing our shoes at the airport and limiting ourselves to those tiny, trial-size containers of toothpaste, shaving cream and lotion are enough to ensure a safe flight. For passengers on Northwest Flight 253, this was not the case.

One solution -- expensive and intrusive, but effective -- would be to make use of new airport screening technology mandatory. Either a "whole-body imaging" scanner, which gives a much more detailed picture than a regular metal detector, or a "sniffer" machine, which analyzes trace chemicals, would have been likely to detect the explosives that Abdulmutallab allegedly was carrying.

In this instance, however, the system seems to have malfunctioned well before Abdulmutallab reached Amsterdam's Schiphol airport. Abdulmutallab's father, wealthy Nigerian banker Alhaji Umaru Mutallab, had warned U.S. and Nigerian authorities about his son's increasing radicalization -- information that led U.S. officials to put Abdulmutallab's name on a watch list, along with more than 500,000 other names, but not to revoke his multiple-entry visa or keep him off a Detroit-bound jetliner.

It is an ordeal for anyone from the developing world to obtain a visa to enter the United States. We already turn away multitudes. It will be no small task, but the system needs to be re-engineered to let the right people in and keep the dangerous people out.

When Abdulmutallab allegedly set his lap on fire, there were no air marshals on board to handle the situation. I realize it is not possible to provide an armed federal escort for every single flight. But whatever algorithm officials use to determine which flights get marshals evidently needs improvement.

The second problem we face is much bigger, and there is no real solution in sight.

According to reports of Abdulmutallab's statements to authorities after his arrest, he claims to have gotten the bomb -- and instruction on how and when to use it -- from al-Qaeda operatives in Yemen. As noted previously in this space, and illustrated by a sobering report Monday in The Washington Post, Yemen features prominently in al-Qaeda's expansion plans. Abdulmutallab's story suggests that an infrastructure for indoctrination, training and bomb-making is already in place, and that this ambitious young branch of al-Qaeda is confident enough in its abilities to launch an attack on what the George W. Bush administration infelicitously called the "homeland."

Our enemy apparently sees its future in places such as Yemen -- or perhaps Somalia, a failed state for almost two decades, where militant fundamentalist Islam is on the march. The enemy's leadership is believed to be ensconced in remote areas of Pakistan, beyond the government's reach. Yet the United States will soon have about 100,000 troops chasing shadows in Afghanistan, where al-Qaeda's presence is now minimal.

I understand and appreciate the fear that if the Taliban were to take power again, it could invite al-Qaeda back into Afghanistan to set up shop. But I can't escape the uneasy feeling that we're fighting, and escalating, the last war -- while the enemy fights the next one.