ROBERT SHAPLEN HAS SPENT over 30 years in Asia, much of that time as the legendary correspondent of The New Yorker. He arrived, as a war correspondent, in the Philippines in 1944. He was writing of Vietnam even before Graham Green went there to produce The Quiet American in the '50s. He was the growth of American commitment through the '60s. He was still there to witness the American evacuation in 1975. In many ways Shaplen was the dean of the American press corps in Saigon; no one knew more minutely than he the intricate dances of Vietnamese politics. When younger journalists were assigned to Vietnam in the '60s, it was often to Shaplen's work that their editiors referred them.

In The Turning Wheel, Shaplen surveys the recent political, social and economic histories of Vietnam, Cambodia, Laos, Thailand, Burma, Malaysia, Singapore, the Philippines, Korea and Japan. He does not deal directly with China, but the impact of Peking's policies upon each country in the region is discussed as is that of the United States. The book draws on varied sources: government statistics, academic and other studies. It will provide a very useful background source of journalists, businessmen and others interested in the area.

Shaplen begins his book with a chapter on Indochina. Although he does not deal at length with the origins of American policy there, his opinion is clear. "Is still believe . . . that the war was essentially a political rather than a military one, which is to say that it was unwinnable militarily but could have been ameliorated and compromised sooner." As for the domino theory, the thinks today, after Vietnam's invastion of Cambodia, that even if it was always "too simplistic," it still has some validity. "I have always preferred to think in terms of a 'bleeding' theory rather than of falling dominoes, and if the Vietnamese revolution, with fresh blood in its veins, now bled across the Cambodian border into Thailand . . . . all the ASEAN [Association of Southeast Asian Nations comprising Indonesia, Malaysia, the Phillippines, Singapore and Thialand] nations would sooner or later be affected."

Apart from his treatment of Japan, whose history since 1945 Shaplen covers at some length, he deals principally with eventss since 1975, providing an extensive account of the effect that America's defeat and Vietnam's intrasigence has had in the area. Since, like most journalists, he has been unable to visit Cambodia's "road back to civilization will be long and painful."

For Laos, whose bizarre attractions he understands well, he can offer scarcely more hope: If the phi , or spirits thought by the Lao to be everywhere, are to survive, he says they will probaly need "Russian masks and nicknames," so great has been that country's support of the Laotian regime.

He is also pessimistic about Thialand's future, pointing out inter alia that "the flaunting of wealth in Bangkok, a capital whose lack of conscience remains perhaps the gretest impediment to national progress, may yet prove Thailand's ultimate undoing." He is not much more cheerful about Malaysia, with its apparently insoluble racial problems. He asks whether Singapore's Lee Kuan Yew might not apply a quality of grace as well as discipline to his rule, but concludes that "in the contemporary world he knows so well, guts is perhaps more important than grace, and he has plenty of that."

Shaplen is equally gloomy about the futures of both the Philippines and Indonesia; neither government has addresssed its appalling problems of corruption and poverty. In the Philippines he thinks "the revolutionary pendulum could swing further to the authoritarian right, or it could swing left, under some form of communism. But it won't stand still." As for Indonesia, he fears that without appropriate development "it will either break down or blow up again," as in 1965. For Korea, Shapleen points out, the oly long term solution is reunification. He thinks the U.s. should take a lead, encouraging bilateral talks, opening a dialogue with North Korea and enlisting Peking's support to broaden negotiations. To leave the two Koreas to "become stronger militarily and glare down each other's throats is to court disaster."

A Turning Wheel deals most fully with Japan, perhaps because Shaplen was there when MacArthur first formed the postwar society, and he has retained a well-informed affection for the country ever since. He is concerned lest American "neo-isolationism and protectionism" may coincide with or rather lead to resurgence of Japanese nationalism and militarism and points out that much depends on how American redevelops its Pacific role. He hopes to see a new, uncompetitive triangular relationship between Tokyo, Peking and Washington. But he fears that faced with another crisis in Asia, say in Korea, the United States might even use nuclear weapons again "to stem the tide of aggression, or in the mistaken belief that it would put an end to a brush war that threatened to get out of hand." That, he says mildly, "would be a hazardous move, one that could easily trigger a wider nuclear war in Europe and elsewhere."

The author's knowledge and love of Asia are apparent throughout his valuable, somber book. At times his enjoyment of the area is also plain -- as in his description of a crazy trip with a laughing taxi driver through a Manila monsoon, or in his gentle description of Burma, which (like Cambodia before 1970) has managed through neutrality to protect itself against many of the more ghastly ravages of recent years. But on the whole his is sparing with his imagess and his personal recollections. This is perhaps a pity because such a distinguished correspondent must have whole galleries of his mind (and tea chests of note books) crammed with stories, incidents, horrors, jokes, personalities which would bring to life the poignant beauty and the problems of Asia in a way which more strictly political works rarely can. The publishers claim that this book is Shaplen's magnum opus. I suspect that they are wrong and that he must even now be preparing that.