REP. DONALD FRASER (D-Minn.), whose subcommittee is investigating South Korean influence peddling, poses an interesting question. Why did the Nixon administration not pursue more, vigorously CIA and FBI reports in 1971 suggesting that the Koreans were spreading money around and otherwise secretly maneuvering in Washington? "This is a very disturbing record we've developed," he said recently. "It defies explanation."

Perhaps so. Perhaps it will yet be shown that the Nixon administration was guilty of poor judgment or political blindness or something more venal in passing by the intelligence reports. But there are other possibilities. Suppose, for instance, as is suggested by a subcommittee summary of an undisclosed FBI memo based on an undisclosed CIA report, the Koreans funneled $400,000 to the Democratic Party in 1968 - and perhaps almost as much to the Republicans. That's worth knowing. But it is not against the law until 1974 for foreign nationals, as distinguished from foreign agents, to make political contributions. There is also the matter of the reliability of that original CIA report. A subcommittee investigatior says "no evidence has yet been found to substantiate the report about the money of the Democrats." Read that twice.

Presumably Mr. Fraser would not proceed this far down the investigatory trail if he did not expect to hit paydirt at the end. But there is reason to be uneasy about an investigation (and about some of the coverage to which it gives rise) that trades so much on an atmosphere in which the mere mention - and certainly the collective mention - of CIA and FBI and South Korea is considered titillating. It is not that they all have not richly earned skeptical scrutiny. But the Congress and the media still must proceed case by case to establish a specific record. It is important that they do so for their own sake and, on another level, to protect the important security relationship between the United States and South Korea.