In the past two years, as relations between the United States and the Soviet Union have gradually deteriorated from the hey-day of detente six years ago, incidents of harrassment and intimidation of American diplomats, businessmen and journalists here have increased in number and severity.

There is no doubt in the minds of seasoned observers that the incidents constitute a rough barometer of Kremlin feelings toward Washington. In the past two days, two incidents have underscored this notion.

On Monday, the Soviet accused a former U.S. diplomat here having been involved in a CIA plot, allegedly involving a murder, to "stop detente" by espionage. The following day, it was revealed that Soviet police had dragged an American businessman from his car in downtown Moscow and had detained him on a reported smuggling charge.

Both acts are virtually unprecedented. Never before have the Soviets directly accused the CIA of killing a Soviet citizen as part of a spy plot. While businessmen have occasionally been searched at customs points, no one here could remember an incident of such crude intimidation as the seizing of F. Jay Crawford.

There are more than two dozen American companies with representatives here and the arrest of Crawford sent shock waves through this group. Many of them gathered at the embassy commercial office yesterday for a briefing by U.S. officials.

"They're upset and some are scared," said one businessman.

To a degree, the two incidents must seem as seperate examples of the tensions between the two superpowers. Relations between the Carter administration and the Kremlin are in a period of extreme difficulty as the two governments attempt to find a successful way to address each other's concerns and conclude a number of important agreements involving both nuclear weapons and conventional forces.

The case of the diplomat. Martha D. Paterson, whose connection with the CIA has been confirmed is seen by many sources here as a straight Soviet retaliation against the revelation two weeks ago by the U.S. Embassy that it has found Soviet eavesdropping equipment on Embassy grounds.

Both governments in the past have sought to blunt each other's allegations of espionage activity with revelations of their own. But the seriousness of the charge in the Peterson case hints at a new intensity in the Krelmin's approach.

Similarly, the incident involving Crawford a representative of International Harvester, a company with tens of millions of dollars in contracts here and run by an outspoken adovcate of closer U.S. Soviet trade ties, evokes ghosts of the Cold War Stalin era.

Not long ago, such incidents would have been unthinkable. That was in the days when Soviet leader Leonid Brezhnev and President Nixon had found responsive notes of trust and understanding that shaped and softened Soviet-American relations from the 1972 summit through the first months of the Ford administration.

In the spring of 1976, with President Ford beginning to find political troubles wiht detente following Soviet involvement in Angola, harassment began anew for Americans living here. Several U.S. diplomats were jostled and spat upon and warned that "worse could happen" if demonstrations against the Soviet Union in the United States by the Jewish Defense League did not cease. When the league ceased its protests against Soviet treatment of Jews, the harrassment also stopped.

As events have unfolded since, however, the atmosphere here for American correspondents and diplomats especially has been marked by renewed pressure. The principal cause has been Kremlin alarm at the increased contacts between the small, scattered groups of human rights activists here and the reporters. This alarm turned to fury when president Carter made human rights a major issue of his new administration and publicly supported the dissidents.

The KGB secret police neutralized the embassy's specialist in human rights activities by heav-handed surveillance. The state-controlled press began denouncing seversal American correspondents working here at the time: George Krimsly of Associated Press, Alfred W. Friendly Jr. of Newsweek, Chritopher Wren of The New York Times, Peter Osnos of The Washington Post and Robert Toth of The Los Angeles Times.

Krimsky, Friendly and Wren were accused of working for the Central Intelligence Agency, the first time in memory that journalists had been directly accused of working for the CIA. Krimsky was expelled on alleged currency irregularities and Toth was later seized and questioned, allegedly for possessing confidential state documents.

The press campaign against these five has continued, although none works here any longer. Krimsky, Wren and Friendly recently were labeled as CIA agents in a half-hour television show that was a clear warning to viewers to avoid contacts with American correspondents. The campaign against the reporters has been combined with moves against the dissidents, including arrests, intimidation and involuntary emigration.

In the year since Toth was seized, the KGB has repeatedly stopped journalists from taking photos of news events and on several occasions has seized film. CBS correspondent Bernard Redmont has been interfered with three times. Another correspondent was detained for almost five hours by Soviet border guards as he drove back from Poland and many of his notes and research files were seized and not returned.

A Soviet newspaper recently denounced another reporter and other similar icidents have occurred to create an atmosphere of frustration within the small community of reporters.

The recent spate of harassments is in part caused by the unfolding of events: a major trial of dissident leader Yuri Orlov, which triggered many incidents; a series of demonstrations by dissidents and Jews seeking exit visas.

The Soviet reaction to these events leaves little doubt in the minds of many about how the Kremlin currently feels about some of the foreigners it finds residing in its midst.