Has Alternative Explanation to Pan Am 103 Bombing

Lester Coleman, a former employee of the Defense Intelligence Agency, has been held in a New York Detention Center since his return to the U.S. in December of last year.
Coleman charges that there has been a massive international cover-up over the bombing of Pan Am flight 103 that went down over Lockerbie, Scotland in 1988. He says that it was a drug sting operation that went awry.
The U.S. government maintains that Pan Am 103 was bombed by Libyan terrorists.

During the late 1980s, Coleman was stationed with the DIA station in Cyprus. Part of his task was to spy on the activities of another U.S. agency, the DEA. The DEA was operating a number of drug sting operations in the Middle East by allowing "controlled" deliveries of drugs from Lebanon to the U.S. But Coleman discovered that the sting operation was infiltrated by Iranian-financed terrorists who switched a suitcase full of drugs with a suitcase containing a bomb.
Coleman's current jailing is a direct consequence of his whistleblowing. He came forward during the investigation of the 1988 air disaster and gave an affidavit to Pan Am. Three years later he repeated the charges in a book "Trail of the Octopus." After publication of the book, US intelligence chiefs ordered Coleman's arrest on charges of perjury. He went into hiding in Europe with his family but returned late last year because of failing health and to clear his name.
Jailing on perjury charges is rather unusual. Further, if Coleman's claims are inaccurate, he cannot have violated any oath of secrecy.
Coleman's lawyer told the London Telegraph, which has reported on Coleman's claims and his jailing, that "The way the authorities are treating Coleman is a total overreaction. There is no justification for treating him like this. It suggests the authorities are afraid of something, and want to keep him quiet." Indeed, what is the government afraid of? What was the story with those "controlled" drug deliveries and why did the DIA spy on the DEA?