As usual when a government goes into an operation such as the one President Reagan has entered upon in Central America, there is much talk of the dire consequences of failure to do what is being done.
There can be such consequences. There is little doubt, none in my own mind, that the consequences would have been unfortunate for the United States and its friends and allies had Harry Truman failed to do battle for South Korea.
The loss of South Korea would have exposed Japan, since the Korean peninsula is the logical jump-off base for an attack on Japan.
Also, perhaps more important, had the US failed to fight for South Korea the men in the Kremlin might well have concluded that they could safely enter upon other offensive operations equally or more damaging to the Western world. There is evidence that the Soviets were getting ready to invade Yugoslavia when the Americans took up the gauntlet in South Korea. Stalin did not invade Yugoslavia much as he resented Marshal Tito's defection from the Soviet orbit.
Seldom have more dire consequences from failure been predicted than by the Lyndon B. Johnson White House during the Vietnam war. But the US withdrew from Vietnam. Vietnam fell to the communists of North Vietnam. How dire were the consequences?
On the sad side was the story of the refugees escaping as best they could, often unsuccessfully. Those who reached the US alive were the fortunate ones. Also on the negative side was a loss of trade between Western countries and Vietnam.
But there was a positive side. The US withdrawal from Vietnam cleared the way for Richard Nixon's reopening of US relations with China. That in turn made possible China's full and open escape from Moscow. And that in turn tied down 50 Soviet divisions, roughly a quarter of total of Soviet land power, on the Chinese frontier.
US withdrawal from Vietnam produced an improvement in the US position in the overall balance of world power. Roughly half of America's ready military power had been tied down for nearly eight years in Vietnam. After Vietnam that power was freed for use anywhere. The Soviets lost the use of a quarter of their forces for service elsewhere.
Angola was a case where Henry Kissinger, the same one just recalled for Central American service, once (in 1975) wanted greatly to do what President Reagan is now doing in Central America. He wanted to have the CIA send guns, advisers, and support clandestinely to the anticommunist factions to head off another faction supported by Moscow. He predicted dire consequences if Congress refused him permission.
Congress refused the permission. The Soviet-supported faction won, as Mr. Kissinger predicted. It is still in power in Angola and is still being sustained by 18,000 Cuban troops and 200 Soviets.
But Angola continues to do most of its trade with the West. The US takes much of Angola's oil. American companies doing profitable business in Angola favor US recognition. Moscow has the satisfaction of having a client for its arms in the center of Africa. But nothing worse has happened. The domino theory did not operate either from US withdrawal from Vietnam or from the triumph of Moscow's clients in Angola. Communism has not been contagious either in Southeast Asia or in Central Africa.
El Salvador may fall to the communists. It probably will if Congress refuses more aid to the rightist government. A dire consequence much mentioned in Washington is that Moscow, or Havana, could put weapons into El Salvador which could threaten the supply line between the US and its NATO allies in Europe.
In theory, Moscow and Havana could send such unfriendly weapons into El Salvador if El Salvador went communist. But would they? Cuba, El Salvador, and Nicaragua are as close in military terms to the US as Poland, Czechoslovakia, and Hungary are to the Soviet Union. The US would like to see all three free from Soviet domination. But it never moved a soldier or a gun to help them in their respective ordeals.
Would Moscow put valuable and dangerous weapons into Central America where they would be under the gun of US military power which is decisively superior in the area? Moscow tried it once in the ''Cuban missile crisis'' and learned a humiliating lesson. If it repeated the mistake, it would have to be taught the lesson again. The US must not, and certainly would not, tolerate offensive Soviet weapons or forces in the Caribbean.
There probably would be another wave of refugees, but there is one already. There would be another leftist country in the Caribbean. But then they come and go. Jamaica was one for a while, and is now happily back in the Western fold. It would be unpleasant for President Reagan to have it happen in El Salvador while he is in office, but he could blame it on the Democrats for having refused enough funds, which would be substantial political compensation.