A dramatic but scarcely noticed turnabout has occurred over the past decade. Today, nearly half of the major insurgencies around the world are inspired by the political right - some of them directly sponsored by Western powers. Back in the early 1970s, most such guerrilla wars were of leftist origins - many of them sponsored by the Soviets or their allies.
The change reflects in part an increase in Western readiness to challenge the Soviet bloc in exploiting some of the globe's more unstable areas. The East, in turn, finds itself more on the defensive. It no longer has a near monopoly on regional subversion.
The fact that both sides take advantage of local turmoil presents a dilemma to policy planners. They are forced to recognize that exploiting such regional political ferment is a two-edged sword.
For instance, Soviet reversals in the past decade in the Middle East and Africa may have caused disillusion in Moscow about the ease of attaining permanent victories outside Eastern Europe. This in turn seems to have induced a sense of caution regarding new adventures, although it is not at all clear how long this will last.
But the Soviets have not grown permanently less aggressive in the third world. They continue to war in Afghanistan. They vigorously encouraged the recent conversion of Ethiopia's only legal political organization into a communist party. And massive military support to Syria continues.
But whereas in the early 1970s seven of the world's nine major insurgencies were leftist (see accompanying chart), today only four out of 14 are leftist. Except in El Salvador and perhaps the Philippines, none of the current such conflicts appears to be supported directly by the Soviets or their allies. And six of the 14 are rightist in orientation, several of them directly backed by the West and its allies.
All this probably does not mean that a permanent wave of anticom-munism has replaced the anti-Westernism of the previous decade. Nor does the turnabout imply profoundly greater assertiveness in major Western powers.
The West is indeed conspicuously supporting some ongoing guerrilla wars. But domestic political reaction resulting from such involvements - perhaps most noticeable in the current reluctance of the United States Congress to fund further support for the contra rebels fighting the Nicaraguan government - may force a retrenchment. Western democracies have traditionally been fickle when it comes to sustaining a policy of aggressive action beyond their own borders.
A few trends are discernible, however:
* In some areas, local warring forces are so evenly balanced that conflict seems endemic. Given sufficient external support, conflict continues despite temporary victories or defeats of one side or other. Angola, Mozambique, and Nicaragua experienced successful leftist insurgencies in the 1970s. They are now in the throes of rightist counterrevolutions.
* Some pro-Western states in the third world are extremely assertive in matters of ''forward defense'' beyond their borders. South Africa and Israel are the prime examples. The former's support to insurgents in Angola and Mozambique typifies this assertiveness. These states are generally unresponsive to pressures from larger Western states to abandon policies they regard as essential to their security.
* Religion, particularly Islam, has asserted itself as a militant force. Conflicts in Afghanistan, Lebanon, and the Philippines are partially Islamic in inspiration. Iran, Libya, Egypt, and Saudi Arabia have all supported foreign insurrections that represent their respective brands of Islam.
* Long-standing ethnic conflicts are often fueled by external interference of all political hues. Separatists in Ethiopia and Sudan are motivated primarily by ethnic considerations but supported partially by foreign sources.
* The political and moral costs of supporting insurgency are high in a Western democracy. Its purely technical effectiveness, however, is not in dispute. Previous defeats in Vietnam and elsewhere have forced this realization. Although simple weapons are used in a guerrilla war, they do tie up expensive conventional systems. The manpower needed to sustain an insurgency is minor compared with the numbers of regulars required to contain it. And backing indigenous insurrections can enable the sponsoring power to avoid making politically unpopular commitments of its own troops.
* Military organizations now exist in both the West and the East that specialize in either defensive or offensive insurgency tactics. The very existence of these units encourages their use when a target of opportunity presents itself.
* Finally, it is more difficult now for a meddling power to get its way by a simple coup d'etat. Modern repressive methods are far more effective in detecting conspiracy than were those in the decade following World War II. The more prolonged approach of insurgency may become the only alternative for a power bent on effecting a change.
In short, ''revolution'' today is no longer virtually synonymous with a leftist ''people's liberation war.'' The West has discovered the technical efficiency of fomenting insurgency. It has duly proliferated its use, albeit at a political cost at home. In addition, there now are other assertive players on the scene. Countries such as South Africa and militant Islamic powers are prime examples.
Hence, insurgencies are likely to continue or even proliferate in the future, but with diverse sponsors. And a cyclical trend is visible.
A Soviet policy planner, contemplating the merits of supporting an insurrection, can no longer assume stability once a regime is overthrown. A leftist victory may be reversed or damaged in time by a rightist counteraction. Equally, should current rightist insurgencies in such areas as Angola or Nicaragua prevail, armed leftist opposition might reassert itself. The current cycle could well reverse itself.
The lessons of the previous two decades indicate that all too often insurgency has been an effective tool to attack an existing regime. But once in power, the former insurgents may well be equally vulnerable to externally supported counterrevolutionaries. The long-term value of this type of warfare to either East or West is severely limited by this reality.The writer was a government official for two decades before becoming a consultant on international affairs. PRESENT INSURGENCIES Insurgencies in 1984: Country/Type
Papua New Guinea/Ethnic
West Sahara/Nationalist/leftist Insurgencies in 1970s:
Ethiopia (Eritrea,Tigre, Oromo) Ethnic/Nationalist
Rhodesia (now Zimbabwe)/Nationalist/leftist
Southeast Asia, including Laos, South Vietnam, Cambodia/Communist
West Sahara/ Nationalist/leftist