After months of investigation, a government report has concluded that Aldrich H. Ames, the Central Intelligence Agency spymaster convicted earlier this year of handing over U.S. secrets to the former Soviet KGB, managed to escape detection for almost a decade mainly because the spy agency itself covered up the failings of its old boy network.

In a 400-page classified document, the CIA inspector general's office found that Ames exposed 55 clandestine U.S. and allied operations over nine years, far more damage than had been admitted previously. The report blamed one of the worst scandals in the agency's history on what it termed the "almost complete indifference of senior CIA supervisors," who failed to recognize the importance of their losses and did not put "adequate resources" into the internal search for a Soviet mole.

Congress rightly demanded that CIA director R. James Woolsey discipline the officials involved, whose actions clearly put the national security at risk. Yet last week, Mr. Woolsey, who earlier had conceded that Ames' betrayals might have been detected and stopped but for a lack of management attention to his work performance, announced that no agency officials would be demoted or fired, and that only 11 senior CIA officers have been reprimanded for failing to push hard enough to uncover Ames' spying.

In what looks suspiciously like a face-saving slap on the wrist, four officers were given "very serious" letters of reprimand -- warnings that normally are accompanied by demands for early retirement or dismissal. But three of the officials already had retired, and the fourth is due to retire in a few days. Seven other officers were given lesser reprimands. But three of those already are retired. The other four are still working at CIA and will remain.

This whole affair smacks of business as usual. Congress is now faced with the distasteful task of imposing discipline on an intelligence community that simply cannot be trusted to police itself. Worse, the relative immunity from public oversight the agency enjoyed appears to have contributed to a dangerous institutional arrogance that undermined its own effectiveness.

Given the inherent tension between a spy agency's cult of secrecy and the requirement of public accountability in a democratic society, that kind of risk may be unavoidable. But as the Ames affair shows all too clearly, it is one we ignore at our peril.