The memorandum added: ``Since some recent health problems among embassy staff appear similar to EMP (electromagnetic pulse) researchers at Boeing, at MIT (Massachusetts Institute of Technology), and possibly at the Naval Special Weapons Center, comparison of details of exposure and later-occurring pathologies appears warranted.'' Health problems which have been reported among personnel working with electromagnetic pulse equipment include an unusually high incidence of brain tumors and liver diseases. A memorandum prepared by Myers following his 1975 visit to Moscow said, ``Dr. Herbert Pollack, a State Department consulting physician, has found that several members of the embassy display symptoms that are non-specific but have been reported frequently in patients chronically exposed to non-ionizing radiation.'' Such symptoms include headaches, inability to concentrate and fatigue, as well as physiological effects including shifts in the ratios of various blood cells. Soviet intentions remain the foremost unanswered question surrounding irradiation of the embassy. Attempts to figure out the purposes behind the microwave beams have involved specialists at the State Department, CIA, Defense Intelligence Agency, Defense Advanced Research Projects Agency and National Security Agency. The difficulties posed by this task were reflected in a June 6, 1975 letter in which the CIA's Colby told Eagleburger at State: ``We hope that by working together State and CIA technical officers can come up with satisfactory answers to this perennial enigma.'' Three theories have been put forward as possible explanations: _The Soviets were trying to interfere with U.S. electronic intelligence-gathering operations; _The microwaves were used to interact with Soviet eavesdropping devices planted within the embassy; _Or the Soviets were trying to induce psychological, behavioral or physiological effects among American personnel. Mark Garrison, who served as head of the State Department's Soviet desk and then as the Moscow embassy's No. 2 official before retiring in 1980, said in an interview, ``We never did really figure out to my satisfaction what the purpose of the microwaves was. I've got hunches about it, but there was no final, formal finding that was passed down from the technicians.'' ``It's extremely difficult for people running the political side of the (U.S.-Soviet) relationship and the management side to get a good handle on high-tech electronic stuff,'' said Garrison, now director of Brown University's Center for Foreign Policy. Garrison leans toward the electronic jamming theory. However, that explanation has been challenged by Moscow veterans familiar with the military-run electronic intelligence-gathering operations. Retired Army Brig. Gen. R.E. Barber said he ``absolutely cannot accept'' the jamming hypothesis because when he was in Moscow during the mid-1960s the microwaves ``had no effect whatsoever on our activities.'' Samuel Koslov, a non-ionizing radiation specialist who has helped investigate the radiation, believes the beams probably were been intended to interact with Soviet listening devices. ``They (U.S. debugging specialists) still haven't satisfied themselves that they've found all the devices that may have been interacting with that signal. They may have found some of them, but they certainly haven't found all of them,'' said Koslov, a biophysicist at Johns Hopkins University's Applied Physics Laboratory in Laurel, Md. He added, however, that ``there could have been different purposes at different times'' over the 35-year history of the microwaves problem. Regarding possible anti-personnel uses of microwave radiation, Koslov said, ``I wouldn't say that it is impossible to produce psychological effects, but you would have to do it with very different kinds of signals, much higher power than what you have there.'' Other American specialists involved in the investigations have raised the ``mind control'' and weaponry possibilities. Among them was Richard S. Cesaro, who in the mid-1960s was serving as deputy director for advanced sensors at the Pentagon's Advanced Research Projects Agency. Cesaro helped run the classified Pandora Project, in which monkeys were exposed to a ``synthetic Moscow signal'' in a laboratory at Walter Reed Army Institute of Research. Initially, Pandora researchers believed that the irradiation had caused subtle behavioral effects in the test animals. By mid-1969 consideration was being given to expanding the project to include human subjects. Later, however, re-analysis of the experimental data raised doubts about its validity. A scientific review panel decided in 1970 that the project should be disbanded. Nevertheless, Cesaro, in an interview prior to his death two years ago, contended that ``in our experiments we did some remarkable things. And there was no question in my mind that you can get into the brain with microwaves.'' Arguing that the Soviet bloc's investment of funds, personnel and laboratory facilities in research on non-ionizing radiation bioeffects has far outstripped the West's, he said, ``I look at it as still a major, serious, unsettled threat to the security of the United States.'' ``If you really make the breakthrough, you've got something better than any bomb ever built, because when you finally come down the line you're talking about controlling people's minds,'' Cesaro said. Another research effort whose results proved highly controversial was the State Department's secret genetic testing program, carried out from 1966 to 1969 under the cover name of the ``Moscow Viral Study.'' This project involved taking blood samples from embassy personnel exposed to the Soviet microwaves and from a control group and analyzing the white blood cells for possible chromosomal damage. Those who were tested were not told the actual purpose, but instead were given the cover story about checking for a viral condition. By late 1968 concern about results of the cytogenetic testing had mounted among senior officials privy to the findings, and the university contractor, Dr. Cecil Jacobson, urged that the study be continued and expanded. In mid-1969, however, the State Department abruptly decided to terminate the study, after having test slides re-examined by four outside consultants. Nicholas H. Steneck, a University of Michigan history professor and author of a book, ``The Microwave Debate,'' said the cytogenetic testing program ``was set aside on the shoddiest and shakiest of grounds.'' ``At the very least there was scientific ambiguity, because there were some researchers who said the techniques were very good and that they did see effects,'' Steneck said. ``If nothing else, on the basis of that you do a follow-up study _ you don't just crank it down.'' Asked about Steneck's remarks, Dr. Charles E. Brodine, State Department assistant medical director for environmental health and preventive medicine, said he had not been with the department at the time of the genetic testing program and would prefer not to comment. Government officials and outside experts say one of the biggest lessons learned from the microwave problem was that it was a mistake to keep the radiation secret from most employees until February 1976, when the State Department began briefing current, former and prospective Moscow personnel. ``The main lesson is to be upfront with employees about things that they might consider to affect their health and well-being,'' said Garrison, the former State Department official.