Over the years, defense contractors have developed a well-earned reputation for indulging in a variety of shoddy practices involving waste and unethical shortcuts.

But now this industry seems to have outdone itself with a scandal that exceeds all previous ones - and that's saying a lot.The dimensions of the scandal became apparent this week with surprise searches by federal strike teams of the offices of two senior Pentagon officials and more than a dozen major defense firms in as many different states.

Though the investigation has not yet produced arrests or formal charges, it still should raise plenty of eyebrows because the two-year-old probe of bribery and fraud cuts across all military services.

That easily makes this episode a scandal that is, in the words of one top military official, possibly "the largest procurement fraud in history."

The military programs involved in the investigation include the F-404 engines used aboard the Navy's F-18 jet fighter and that reportedly power the Air Force's secret F-19 Stealth fighter, electronics systems used on the V-22 tilt-rotor aircraft the Navy is developing, and communication and navigation systems used aboard Navy ships and planes.

Despite its massive scale, this scandal might have gone unnoticed if it had not been for one person who spoke out - a former Navy department employee who talked to the Naval Investigative Service.

As long as enormous sums of money are at stake, defense contracts will always be accompanied by strong temptations to bend the rules. Sadly, Americans evidently can't afford to assume that everyone involved in defense procurement has clean hands. Clearly, the whole process bears constant monitoring.

More than money is at stake. So is national security. After all, those who resort to fraud and bribery can't undercut honest bidders without short-changing the taxpayers. And the taxpayers can't be short-changed on military projects without giving this country less than all it's paying for in the way of defense.

Militarily as well as morally, fraud in defense procurement constitutes a chink in America's armor. This country must not tolerate even a little of it, let alone abuse on the wholesale scale indicated by the latest investigation.