Armed Truce: THE BEGINNINGS OF THE COLD WAR, 1945-46, by Hugh Thomas (Atheneum: $27.50; 667 pp.)

On Feb. 9, 1946, Joseph Stalin addressed 4,000 Communist Party members, military officers and officials--”the upper class of the first classless nation”--in Moscow’s Bolshoi Theater. It was a notable speech on several accounts, one being that it proclaimed the previous year’s Allied triumph of arms over Germany as almost exclusively a victory for the Soviet system, another for its signal that Russians should once again be thinking of themselves as the “revolutionary vanguard” in a great international struggle. In Fulton, Mo., three weeks later, Winston Churchill, out of office after leading Britain through five years of war, spoke his famous words about an Iron Curtain having descended across Europe. Each in his own way, Stalin and Churchill were giving formal recognition to what had already become unmistakable and, as events proved, irreversible. The Cold War was well under way.

That confrontation is now in its fifth decade. It has inspired a voluminous literature, much of it aimed at propping up the most dubious of theses, some of it historical analysis of a high order. Hugh Thomas’ history of the earliest years of the Cold War--a term whose first contemporary use he traces to George Orwell--falls emphatically into the latter category. Meticulously researched, its judgments firmly supported by a solid marshaling of facts, fluent in narrative, it is an important and rewarding work. There is something to be learned from it on every page. Another volume and possibly more is promised. Like Thomas’ history of the Spanish civil war, it is likely to remain of enduring value.

Thomas uses a wide-angle lens, scrutinizing the mid-1940s political scene in virtually every European country affected by the war, looking as well at conditions in Japan, Korea, China and Indochina as the war in Asia came to an end. In brief and deft sketches he portrays the major and second-rank figures who found themselves shaping a new world. The Soviet leadership, dominated by Stalin and guided by a combination of Russian imperialism and Marxist-Leninist ideology, had a generally clear sense of how it wanted that world to look and what had to be done to achieve Soviet objectives. Those who played leading and advisory roles in Britain and the United States, with a few notable exceptions, proved to be far less prepared for the new challenge.

The Soviets were skilled in the use of deception and the cold application of military power and raw brutality--including torture, murder and deportations on a mass scale from Eastern Europe--to get what they wanted. The United States, which rushed to demobilize as soon as the war ended and which for some years after lacked even a centralized intelligence system to provide information and analysis about the new threat, found itself not only largely powerless to respond effectively but divided and confused in its views about what should be done. It could only argue and protest, and even that was not always done with a clear voice.

The American problem, notes Thomas, was that it had been painfully slow to recognize the ideological element in Soviet policy, an ignorance or lack of attentiveness that deeply affected the course of the wartime alliance. Some knew better, among them the astute and farsighted George Kennan, who as early as 1944 had argued for a showdown with the Soviet Union as Stalin’s faithlessness over Poland became apparent. Churchill similarly grasped the reality of Soviet ambitions and duplicity as they were unveiled in Poland. For a time, Churchill considered halting lend-lease convoys to Russia to try to win fidelity to the agreements that Stalin had made.

In the end, nothing was done, to the regret even of some Russians like the former Foreign Minister Maxim Litvinov, who quietly complained to prominent Americans in Moscow in the mid-1940s that the West had waited too long to act, that it should have begun opposing Soviet policies three years earlier. Nothing was done because the United States had been too slow to recognize the dynamics of Soviet policy, because the idealism of the war years prompted a high degree of wishful thinking about what the future should hold, because the United States had run down its military power and in any case would probably have had no taste for using it to oppose the Soviet takeover in Europe and northern Korea. The Soviets were not interested in conciliation. They had an agenda, devised long before the West began giving the attention it should have to the postwar world, and to a large extent they fulfilled it.