It is the stuff of spy novels. Sept. 23, 1983: At a restaurant in New York City's Gulf & Western Building, an American graduate student and a Bulgarian official sit down to dinner. They order duck and filet of sole.
They talk. Eventually, secret documents on American nuclear weapons are passed across the table. Money is passed in the opposite direction.
A concealed camera is clicking away. A video camera focuses in from another angle. The table is bugged for sound.
Later, the Bulgarian emerges from the Gulf & Western Building carrying the secret documents. He is immediately arrested by the FBI.
Nov. 4, 1983: In Boston, six Federal Bureau of Investigation agents specially trained for counterintelligence operations mingle with the crowd at a scientific convention. Their target: an East German physicist.
He has been under constant surveillance since he arrived at Logan Airport from Mexico City three days earlier.
The physicist is suspected of being a technical expert for the Ministry of State Security, East Germany's intelligence organization. He is alleged to have paid more than $10,000 over the past year to a United States Navy employee for defense secrets. Eventually these agents, too, move in for the arrest.
In both cases the FBI had good information about what was going on: Both the American graduate student and the Navy employee were cooperating secretly with the US government. They had become civilian double agents of sorts - playing the American renegade trading in US secrets for a quick buck. In fact, they were staying in constant, quiet contact with the FBI.
These are but two of several recent successes scored by the US intelligence community and other government agencies in countering what the Central Intelligence Agency has called ''a massive, well planned, and well managed'' assault on American high technology and defense systems by the Soviet KGB and Warsaw Pact intelligence organizations.
Earlier this month a shipment of American computer equipment was intercepted in Sweden prior to its being shipped to the Soviet Union. Defense Secretary Caspar Weinberger, who requested the computer cargo be returned to the US, said that the computers had military applications and that their shipment to the Soviet Union could cause ''substantial damage'' to US national security.
It is no secret that the plans and components of some of America's most sophisticated and sensitive weapons and technologies have found their way into the hands of Soviet scientists and military planners.
It did not happen by accident. Intelligence experts say that the Soviet Committee for State Security (KGB), and the lesser-known Chief Intelligence Directorate of the Soviet General Staff (GRU), maintain a detailed ''shopping list'' for Western technology.
''The Soviets and their surrogates buy nothing they don't have a specific, well-defined need for. They know exactly what they want - right down to the model number - and what they want is part of a carefully crafted design,'' Lara H. Baker of Los Alamos National Laboratory told a Senate committee last year.
The KGB is reported to have committed 50,000 agents worldwide to the task of satisfying their shopping list.
To do so, Soviet and other East Bloc personnel use techniques ranging from legal purchases, to theft, bribery, and espionage. They subscribe to and scrutinize each of the 80,000 official US government publications printed each year. They sometimes even resort to invoking the Freedom of Information Act.
By all accounts they have been extremely successful.
American technology has saved the Soviets ''hundreds of millions of dollars in research and development costs and years in research and development lead time,'' according to a 1982 CIA study.
The report notes that acquisitions of US technology have not only permitted the Soviets to design increasingly accurate weapons but also to incorporate countermeasures to American weapons systems in their early stages of development.
In many cases they could not have done it without American technology as well as the help of Americans working for the Soviets on the inside. Some examples:
* The material comprising the nose cones of Soviet nuclear missiles was originally an American patent.
* A Russian version of the American AWACS surveillance plane is now on drawing boards in the Soviet Union. The plane itself - the Soviet Il-86 - looks like an American-designed Boeing 747. The CIA says the Soviet plane is very similar to the US AWACS.
* The Soviet-built SA-7 antiaircraft missile contains technical features of the US-developed Redeye missile system. (The SA-7 was believed to have been the weapon that Syria used to shoot down two American jets over Lebanon earlier this month.)
* There are striking similarities, according to the CIA, between US Minuteman nuclear missile silos and SS-13 nuclear missile silos in the Soviet Union.
There are an estimated 3,000 Soviet and East European officials serving in various capacities in the United States, primarily as embassy, consulate, or trade mission staff members or as representatives to the United Nations.
Of those officials, the FBI estimates that between 30 and 40 percent - approximately 1,000 to 1,200 people - are directly involved in intelligence work.
The estimate includes officials in various posts representing the Soviet-allied states of East Germany, Bulgaria, Poland, Hungary, Romania, and Czechoslovakia. According to experts, the intelligence-gathering activities of the Soviet bloc states are coordinated with and often directed by the KGB.
Some observers say the FBI's estimate is conservative.
''According to every single (Soviet) defector I've debriefed for the US government, and of what I know about this, at least 60 percent of those people stationed in this country are either KGB or GRU agents,'' says Miles Costick, a Defense Department consultant and director of the Washington-based Institute of Strategic Trade.
In addition to diplomats and other officials, there are also large numbers of East Bloc businessmen, tourists, visiting scientists and scholars, as well as immigrants scattered across the country. The number of these individuals fluctuates from year to year, and it is difficult to monitor who among them might be an intelligence agent or a Soviet ''sleeper'' agent.
While the movement of Soviet officials and journalists is restricted by the State Department in certain parts of the US, there are no such travel restrictions on East European officials. The restrictions, therefore, only limit direct Soviet access to areas where sensitive facilities, projects, or research may be located.
Last month, in its first revision of restricted areas since 1967, the State Department declared California's Silicon Valley, a world center for high technology research, off limits for Soviet travel.
In the past two years, the State Department has publicly announced the expulsion of at least six Soviet officials for spying. They were: Soviet Military Attache Vasiliy Chitov, in February 1982; military attache Yevgeniy Barmyantsev, UN mission official Alexander N. Mikheyev, and UN mission official Oleg V. Konstantinov, all in April 1983; and attache Anatoly Y. Skripko and attache Yuri P. Leonov, both in August 1983.
But this is only a partial list. Not all expulsions are publicized. And according to a State Department spokesman, statistics on the total number of Soviet and other officials expelled from the US for spying are classified.
Elsewhere in the world it has also been a busy year for Soviet expulsions. In April, France expelled 47 Soviet officials and journalists accused of spying. Soviet officials were expelled as well from Britain, West Germany, Denmark, Italy, Spain, Switzerland, Belgium, the Netherlands, Ireland, Australia, Japan, and Thailand. As a result, close to 100 Soviet officials total have been declared persona non grata and returned to Moscow this year.
The expulsions came as part of an effort to stem the illicit flow of Western high technology to the East Bloc.
The FBI, which is responsible for counterintelligence efforts in the US, is tight-lipped about its operations. But intelligence experts indicate that not all known spies are expelled from the country or are even confronted and arrested by the FBI.
In some cases when a foreign agent is identified he is permitted to continue to operate in the US, though he is placed under close surveillance. The idea is that his continued operations will help uncover a broader spy network.