While terrorists were planning the bombing of the World Trade Center in 1993, FBI agents received taped phone conversations of one of the plotters, Palestinian Ahmad Ajaj. He was talking about explosives.

But the agents didn't speak Arabic, and what might have become a vital tool in averting disaster was instead relegated to a backlog of items needing translation.

Then the bomb exploded, killing six and injuring more than 1,000. The translated tapes didn't come to light until Ajaj's trial.

In the wake of last week's far more devastating terrorist attacks, authorities worry that similar evidence might yet be buried in thick files of untranslated tapes and documents. Their concern illustrates what has become a chronic post-Cold War problem for U.S. law enforcement and intelligence communities in the fight against terrorism - a severe shortage of experts fluent in the languages and cultures of dangerous states and organizations.

FBI Director Robert S. Mueller III put out a public call this week for translators fluent in Arabic and Farsi. Last year, the bureau asked Congress for an additional $5 million for translations, and then-Director Louis J. Freeh cited "short-term, mission-critical criminal and national security investigations."

The National Security Agency, which specializes in international electronic eavesdropping, is asking on its Web site for experts in Asian, Middle Eastern and Slavic languages.

The need for language and cultural reinforcements may be just as great out in the field, especially when agents and investigators journey abroad in search of clues and informants.

"To say we'd be better off with more people immersed in culture and language is like saying a football team would be better off with bigger, stronger guys," said Frank Anderson, a former chief of the CIA's Near East Division. "Every bit of language, every bit of culture that you've got, makes it easier. ... There has been a degradation in recent years. Too little money, too few people."

The shortcoming has been painfully apparent in FBI investigations of bombings on U.S. targets abroad in recent years, said Larry Johnson, a security consultant who is a former deputy director of the State Department's Office of Counterterrorism.

Johnson has compared FBI staffing methods in such cases - the bureau puts out a nationwide call for agents willing to go abroad - to the naivete of Andy Hardy movies, in which teen-agers played by Mickey Rooney and Judy Garland cheerily announce, time after

time, "Let's put on a show!"

As a result, he said, agents arrive in foreign lands not only unable to speak the language, but also unable to read cultural cues, meaning they're more likely to alienate local police.

"The worst of it is, they did it in Dhahran in '96, in East Africa in '98 and then in Yemen after the bombing of the Cole," Johnson said. "You'd think there would be a learning curve, but every time they just throw out a dragnet [for agents]."

During the East Africa investigation, after the bombings of the U.S. embassies in Kenya and Tanzania, FBI agents were stumped in particular by a highly unusual local language and never found anyone with proper security clearance who could translate.

Former CIA operative Reuel Marc Gerecht painted an even bleaker picture of what a threadbare cultural grounding can mean in an article published by Atlantic Monthly two months before the Sept. 11 attack.

Gerecht characterized CIA counterterrorism operations as a deskbound bureaucratic failure, and he quoted another former operative as saying: "The CIA probably doesn't have a single truly qualified Arabic-speaking officer of Middle Eastern background who can play a believable Muslim fundamentalist who would volunteer to spend years of his life with [lousy] food and no women in the mountains of Afghanistan. For Christ's sake, most case officers live in the suburbs of Virginia. We don't do that kind of thing."

Not that any operative holding an American passport, no matter how fluent he might be in the local dialect, would be able to do much about infiltrating an organization such as Osama bin Laden's, says Milt Bearden, a former agency station chief in Pakistan.

"If you're going to do it, it's going to be done with somebody named Mohamed or Ahmed," Bearden said.

And that, Anderson said, means that "you have to recruit people who can do it."