During the past decade -- While the United States has felt guilty about Vietnam, shied away from sending troops into Angola, refused to protect a dictatorial regime in Nicaragua and generally tried to be moral and decent in its foreign policy -- what have those sneaky Russians been up to?

The short answer, given by a growing number of conservative foreign policy thinkers with influence in the Reagan administration, is that the Soviets have been up to no good. The argument goes like this:

While soft-minded liberals in Washington and the capitals of Western Europe were seeking friendship and trade with the Soviet Union, the Soviets conspired throughout the 1970s with terrorists of every stripe to disrupt and disturb the governments of Great Britain, Spain, West Germany, Italy, Turkey, Japan and selected countries in Latin America and Africa. Examples abound.

The beloved English war hero, Earl Mountbatten of Burma, was murdered in 1979 on his fishing boat by a Provisional IRA terroist who learned his bomb-makling craft in Libya under Soviet supervision.

Aldo Moro, the Italian Christian Democrat statesman, was kidnapped and killed in 1978 by terrorists of the Red Brigades, the radical left underground organization whose leaders trained in Soviet KGB camps in Czechoslovakia and Soviet-supported terrorist camps in South Yemen.

The legendary terrorist "Carlos the Jackal," who helped organize the massacre of Israeli athletes at the 1972 Olympcis in Munich and in 1975 led a kidnapping squad that seized 11 Arab oil ministers in Vienna, learned how to ply his bloody trade in three special training camps in the U.S.S.R.

There you have it: a conspiracy. Carlos the cold-eye killer drinks vodka with the KGB. The provisional IRA slaughters helpless school girls with Soviet-made Kalashnikov assault rifles. The violence-crazed Baader-Meinhof Gang blows up West German banks for the furtherance of Soviet world domination. The conspiracy theory of terrorism, with the Russians as the bad guys, has an intoxicating political appeal in this city where Ronald Reagan reigns. Reagan himself claims the Soviets reserve; the right "to commit any crime, to lie, to cheat" to further their goal of world domination.

Secretary of State Alexander Haig, the soldier turned diplomat, accused the Soviets of "training, funding and equipping" the forces of worldwide terrorism. The blue-eyed former general has his own personal reasons for hating terrorists, reasons concerning his own hide. In Belgium in June 1979, he barely escaped an assassination attempt by unidentified terrorists who blew a 10-foot-wide hole in a bridge that Haig's sedan was crossing. That near miss, along with global-policy considerations, may explain Haig's decision to replace human rights with international terrorism as the major concern of U.S. foreign policy.

The conspiracy theory seems so perfectly tailored for newly powerful Republican hard-liners that Democrats who used to run U.S. foreign policy (and who now stand accused of ignoring Soviet involvement in terrorism) question whether the "Russians did it" theory is based on genuine intelligence information or on anti-Communist conservatism that's welded to a keen sense of what the electorate wants to hear.

"I have a feeling there is a lot of loose talk going around with very little support," says former United Nations Ambassador Donald F. McHenry. "It has the pugent smell of politics."

Whatever its motivation, the Reagan administration's finger-pointing has provoked the Soviet Union into one of its more hyperbolic, self-righteous rejoinders since the Cold War. Soviet Defense Minister Dmitri Ustinov said last month the U.S. accusations were an "evil-minded deception" to cover up Western subversion in Poland and other Communist countries. "Terrorism is the weapon of extremism and neofascism, one of the darkets symptons of the moral and political crisis of capitalist society," Ustinov said.

While the rhetoric of terrorism has become politicized and twisted to suit nationalistic purposes, there is no question that terrorism itself is a growing world problem. Between January 1968 and October 1980, the State Department says there were 7,300 terrorist incidents around the world. More than a third of these were directed against American citizens or installations. During the 1970s, 3,277 persons were killed, according to one estimate. The rate of terrorism has increased almost every year in the past decade, with growing numbers of deaths in terrorist incidents. It is worth noting that only 12 terrorist incident have occurred in the Soviet bloc in the past decade.

Even more than increased incidents of terrorism, the Unites States, as well as all Western democracies, fear that nations like Libya will develop nuclear weapons and indiscriminately peddle them to any terrorist group. Worst-cast scenarios that have been reviewed by the Reagan administration descibe terrorists armed with nuclear weapons blackmailing the United Statesby threatening to vaporize New York City.

The Reagan-Haig inclination to favor a Russian - under - every - bush school of foreign policy has caused considerable grumbling and squirming lately at the State Department and the Central Intelligence Agency, which are supposed to know who is responsible for international terrorism. Neither State nor the CIA, according to sources, has much hard information directly linking the Soviets with terrorist groups such as the Red Brigades or the Japanese Red Army. Haig's recent orders to step up the search for such information has, according to a highly placed source, put "the American intelligence community in a terrible political bind. the CIA has been requested to look harder. When they come back and say it isn't true, that they don't see the hand of Russia anywhere, they're told Goddam it, you are either stupid or you aren't trying.'"

Into this politics-besmirched tableau now enters Claire Sterling, a respected free-lance American journalist who has lived in Italy for 30 years. She claims in her new book The Terror Network (a chapter of which is excerpted in this issue of The Washington Post Magazine) that Western governments have been telling "bland lies" about terrorism for years and that the Soviets are up to their ears in providing arms, training and at times direction for terrorists across Western Europe.

"The Kremlin took an avuncular interest in terrorist "adventurers" of every alarming shade. Practically every . . . sort of armed guerrilla group bent on destroying the vital centers of multinational imperialism has been able since 1968 to count on a discreetly sympathetic ear in Moscow," Sterling writes. Although the publication of her book seems proptiously timed to support Haig's position on terrorism, Sterling says she has no connection with the Reagan administration.

Sterling, a correspondent for the old The Reporter magazine and a frequent contributor to The Atlantic and the opposite editorial page of The Washington Post, says there is enough damning evidence against the Soviets "to pole-ax the reader" and her book does just that. With detailed reporting gleaned from two years of travel in 10 Western European countries, Sterling convincingly establishes links between terrorists in Itay, West Germany, Ireland, Spain and Turkey. The links are the Palestinians, the Libyians and the Cubans, who have trained, armed and given sanctuary to terrorists throuhgout the 1970s.

During "Terror Decade I," Sterling claims, nearly every big-name band of international terrorists -- Red Brigades, Baader-Meinhof gang, Provisional IRA, South Moluccans, Japanese Red Army, Iranian terrorists, Turkish People's Liberation Army, Spain's ETA-Militar, Popular Front for the Liberation of Palestine and Fatah, the military arm of the Palestine Liberation Organization -- got together in Cuba, South Yemen, Libya, Algeria, Syria or Lebanon to learn how to kill, bomb, forge documents and fire heat-seeking missiles. Sterling says the focus in the training camps was on efficient terror: the most worldwide television coverage for the bloodiest outrages with the least possible cost in materials and terrorist lives. To speed the training, rampant ideological disagreements among the sometimes illiterate, often psychopathic terrorists were downplayed.

The Soviets use their puppets -- the Palestinians, Libyans and especially the Cubans -- in a grand scheme to support world terrorism, Sterling argues. She claims the Soviets base their faith in terrorist violence on this classic Marxist scenario: terrorist kill and bomb, forcing the police in a Western democracy to crack down on individual freedoms. The repressive police state breeds resentment and makes the masses ripe for Communist revolution.

"It is the disruption and the distrurbing element that interests the Russians, not the ideology of the terrorist groups themselves," says Sterling. "If the terrorists are slaughtered and killed who cares? Not the Russians. They are not concerned with immediate seizure of power."

Although she admits in her book that she has very little information on direct contacts between the Soviets and Western European terrorists, Sterling says she doesn't need it. "I rely on the historic positions take by the Soviet Union," she says.

The current Soviet leadership has an abiding faith in terrorism, Sterling says, which grows out of the remarkably successful terror tactics of the Bolsheviks in crippling czarist Russia before the 1917 revolution. Sterling's theorizing about the historic origins of the Soviets' alleged fascination with terrorism could probably be dismissed as nothing more than journalistic license if there were not senior advisers in the Reagan White House who take these theories very seriously. The chief adviser for Soviet affairs on Reagan's National Security Council is Richard Pipes, a former professor of Soviet history at Harvard who believes that the Soviets have obsessive faith in the power of terrorism to precipitate revolution.

"This experience [Bolshevik terrorism between 1879 and 1917] left an indelible imprint on the minds of the Soviet leadership. This cannot be overemphasized," Pipes said at a conference on international terrorism in 1979. "Nearly all the elements of Soviet global strategy are esentially an adaptation to foreign policy of [terrorist] methods which had been learned by the Bolsheviks and their allies when they were in the underground fighting the Imperial regime."

In The Terror Network, Sterling serves up some tantalizing and occasionally lurid bits of information, claiming that a high-level Palestinian leader is a KGB operative and that the patron saint of Italian terrorism suffered from "a shriveled penis." Yet most of the information and arguments in her book can be found in scholarly works on terrorism written by conservative adademics at think tanks such at The Heritage Foundation, currently in favor with the Reagan administration.

State Department officials and research organizations such as the Rand Corporation agree with Sterling and the conservative academics that the Soviets give military support to so-called "national liberation" movements such as the PLO in the Middle East and SWAPO, the Southwest African People's Organization, something that the Soviets themselves freely admit. They also say there is evidence that the Palestinians and Cubans have received military training in Moscow and that the Palestinians and Cubans, along with the Libyans, have provided training to West European terrorists. But -- and this is the key objection to Sterling and other hard-liners on terrorism -- sources in the State Department and other experts protest that there is no hard evidence of direct Soviet support, control or a master plan by Moscow for European terrorists to destablize the West.

"The critical question is whether the Soviet Union by design through support for the Palestinians and selling arms to the Libyans wants to give support to the terrorists in Western Europe," says Brian Jenkins, director of the Rand Corporations's research program in political violence and terrorism.

Echoing U.S. intelligence officials who are sweating because they don't have the information that Haig wants to hear, Jenkins says: "I can't give you the definitive answers [about the existence of a conspiracy] because I don't know. I haven't seen the evidence."

Any explanation of the worldwide epidemic of terrorism that relies on a Soviet conspiracy strikes the State Department and many longtime students of terrorism as naive. A conspiracy theory of terrorism will probably play well in Peoria, providing an easily grasped explanation for a vexing international problem, as well as providing a popular villain -- those diabolically omnipotent Russians. But many experts say terrorism is just not that simple.

"When you deal with the causes of terrorism everything very quickly gets muddy," says Jenkins. "I almost wish sometimes that there was a goddam central conspiracy in terrorism and then we could do something about it."

The causes of terrorism are inextricably bound to the indigenous economic, racial and political currents running through the countries where terrorism strike. The Palestinians want their homeland back from Israel. The IRA wants to shed the Protestant majority in Ulster that was violently planted there by the English. The Basque separatists want liberation from the Spanish government and a measure of revenge against the Franco regime that executed nearly 10 percent of the local population. Urban West German youths have been alienated to the point of violence by a consumercrazed, materialistic culture. Italy has a legacy back to the 19th century of underground resistance. International terrorism is a messy, complex business.

"It is not nearly so romantic to think about these things as it is to think about Carlos the master terrorist sitting down to dinner with the KGB," says Ernest Evans, a fellow at the Harvard Center for International Affairs who specializes in the politics of radical movements and has written a recent book about terrorism, Calling a Truce to Terror.

The stunning lack of sophistication or success among terrorists in Western Europe -- members of the Baader-Meinhof Gang are nearly all dead or in jail, the ranks of the Red Brigades in Italy have been decimated by imprisonment and defection -- leads State Department officials and other experts to doubt any significant Soviet role there. Sterling's assertion that the PLO responds to "Moscow's every whim in foreign policy" is termed "absurd" by experts who note that the Palestinians have access to virtually all the Arab money they want.

"Considering the Soviet Union's lack of friends in the Arab world," says Evans, "a good argument could be made for the PLO having great leverage over the Russians."

There is no question that Western European terrorists use Soviet-made weapons or that the Soviets make "a habit of fishing in troubled waters," according to Evans. "But the idea that terrorism would go away except for the Soviets is a very dangerous delusion. No one needs the Soviet Union to find small arms and grenades in Europe. These terrorists movements would be able to support themselves without the Soviets."

One cannot expect anything but smug put-downs and whining from the State Department officials and private researchers who've underestimated the Soviet role in terrorism for the past 10 years, according to Sterling and other conservative academics.

"They are scared in the [State Department and CIA] bureaucracy because if Haig is right about the Russians, then they have failed in their jobs," says Michael Ledeen, executive editor of The Washington Quarterly. Ledeen believes the U.S.S.R. is "the fomenter, supporter and creator of terrorism" worldwide. Both Sterling and Ledeen claim that Western governments know far more about the Soviet role in terrorism than they make public (which the State Department denies). They argue that until Haig blew the whistle on the Soviets in his Jan. 28 press conference there'd been a conspiracy of silence caused by, among other things, fear of angering the Soviets, fear of angering the Libyans and other oil-suppliers sympathetic to the Palestinians and by wrong-headed liberal notions about how the Soviets, underneath it all, are nice guys.

"The risk of disbelief in a Russian role in terrorism has been so great in Western liberal-minded countries," Sterling says. "Leftists in Europe would be outraged by the mere mention of this. The cover-up of facts in Europe has gone to egregious degrees. The State Department is not doing a good job in either gathering information or analyzing it."

Like anyone accused of doing lousy work, State Department intelligence analysts bristle under the criticism of outsiders who say they've ignored and covered up evidence of a Soviet role in terrorism. But a measure of how seriously the department, under the thumb of a new boss, takes those critics is that Ledeen was invited recently to Foggy Bottom to tell intelligence officials, among other things, that Western governments have been concealing information on terrorism. "That never would have happened before Haig spoke out," Ledeen says.

According to Sterling and Ledeen, the American intelligence community has failed to notice the Soviets because, before it makes any accusations, it persists in demanding the kind of evidence that would stand up in court. For example, Sterling points to terrorist training camps that the State Department acknowledges are operating in South Yemen, a country dominated by the Soviets. "It is not possible to explain South Yemen without concluding that terrorism is part of Soviet policy," Sterling says. State Department sources say that while the Soviets may be "irresponsible" for allowing the training camps to operate in South Yemen, they cannot be accused of participating in a terrorist conspiracy.

In her book, Sterling claims that waiting for irrefutable proof of Soviet involvement, which the U.S. is "unlikely to get and [does] not really need," has "preserved the terrorists' title to legitimacy -- their license to kill."

The Soviet-conspiracy theory of terrorism could backfire in bloody ways, but Reagan officials are understandably reluctant to talk about that. Repressive South American regimes could choose to interpret Haig's tough talk on terrorism as license for murdering political opponents. South American journalists have already expressed fear that military leaders could shoot leftists with impunity and claim that the dead were little more than Soviets in disguise.

According to Evans, the terrorist expert at Harvard, regimes in Argentina and Guatemala could use the Reagan-Haig hard-line as a justification for snuffing out even non-violent, moderate opponents. "In Argentina and Guatemala there is a tendency among the leadership to think that every time you have a political problem you go kill the Christian Democrats. A sudden crackdown on the violent liberal left usually fails because the government can't find the real terrorists (who go underground) and the government settles for killing the moderates."

Even Ledeen, the conservative editor of Washington Quarterly who sees the handiwork of Soviet terrorist policy around the world, admits there may be a problem. "The right-wing governments might mistakenly draw the conclusion that it is okay to kill and torture any kind of terrorists," he says.

The State Department now attempts to draw a distinction between genuine "national liberation" groups such as the PLO and anarchistic terrorists such as the Japanese Red Army. The national liberation groups, with their historical claim to a homeland and specific plans for establishing a new government, have a legitimacy that the Baader-Meinhof Gang and the Red Brigades, with their often incomprehensible Marxist goals, do not. Israeli Prime Minister Menachem Begin and Carlos the Jackal have both used terrorist tactics during their careers, but there was an obvious difference between their goals. This distinction, however, can easily disintegrate under a conspiracy theory that reduces all terrorists to Soviet Stooges.

A monochromatic world view of terrorism can be used, according to State Department sources and other experts, by countries such as Isreal and South Africa to dismiss any demands by the PLO and SWAPO for an autonomous homeland.

"There are professional apologists for Israel and the South Africans who can argue that their opponents do not represent national liberation efforts, that they are simply creations of the Russians," says Evans.

Finally, there is concern among foreign policy veterans of a boomerang effect -- accusing the Soviets of terrorist atrocities without detailed proof opens the United States to similar accusations. The United States sends arms and money to the civilian-military junta in El Salvador, which has been accused of involvement in the murder of four American churchwomen, and the Soviets -- using the same loose standards of proof as the United States -- can accuse the Americans of a terrorist policy that condones murdering nuns. The same argument can be made against the U.S. support of Afghan freedom fighters or Polish unionists.

"This is the kind of thing I had to fight every day," says former U.N. ambassador McHenry. "They (Soviets and other American adversaries) say we were part of and condoned the torture of Iranian people. I don't buy that. There is a dangerous tendency here to overgeneralize and resort to rather emotional language."

While few longtime observers of the Soviets say they are surprised by any underhanded, conniving Soviet tricks -- including support of terrorism -- they also fear that indiscreet rantings about a 10-foot-tall Soviet boogeyman as the cause of all world terrorism is extremely hazardous. The rantings seem to feed a mutual American-Soviet belligerence while, for the most part, ignoring the root causes of terrorism and glossing over any rigorous definition of what a terrorist is.

Classically it is said that one nation's freedom fighter is another's terrorist. National interests twist the definitions of terrorism. The United States, for example, accused the government of Chile two years ago of supporting "acts of international terrorism" for its refusal to extradite or prosecute three Chileans accused in the assassination of exile leader Orlando Letelier. To punish Chile, the U.S. imposed economic and diplomatic sanctions. But now, the sanctions have been lifted to secure what the State Department calls U.S. security interests. With the Reagan administration hungry for friends in South America, the terrorism of Chile has been defined out of existence.

In the slippery world of international diplomacy, where terrorists are suddenly friends, any nation accusing its adversary of a terrorist conspiracy cannot easily escape the label "hypocrite.