FIDEL CASTRO is not the fiery young revolutionary who in January 1959 rode into Havana on a tank and soon virtually declared war on the other Latin American governments. Now a 62-year-old gray beard, Castro is increasingly reaching out to establish normal ties with the same governments he once vowed to overthrow. He now enjoys full diplomatic and trade relations with most Latin American countries. Perhaps nothing better illustrates Castro's new status and attitudes than his visit to Mexico last month for the inauguration of President Salinas. There he was, the former pariah, sitting side by side with the other chief executives of the hemisphere. And what he once would have welcomed as the prelude to revolutionary upheaval, in Mexico he warned against. Unless the debt problem and other elements of Latin America's economic crisis were dealt with quickly and effectively, he said in a public statement, several countries might soon reach the point of social explosion - an eventuality he clearly saw as undesirable.
For the first time, Castro is older than the reigning Soviet leader. That doubtless has something to do with the fact that the two have changed places ideologically. Once it was Castro, the young maverick, who challenged the Marxist/Leninist orthodoxy of the rigid old men in the Kremlin. Now, a younger, more innovative Soviet leader is bringing about sweeping changes and turning Marxism/Leninism on its head, while Castro insists on orthodoxy.
That does not place any unbearable strains on Soviet-Cuban relations, however. Castro rejects perestroika and glasnost as policies for Cuba, but that is well within the limits of disagreement tolerated by the relationship. The Soviets want Cuba to make better use of their economic assistance, but how Castro accomplishes that is essentially his affair.
By the same token, however, arrangements in the Soviet Union are Gorbachev's responsibility. He cannot but resent Castro's publicly-expressed doubts about Soviet reforms. One of his purposes in scheduling a state visit to Cuba last month was probably to insist that Castro keep his reservations to himself.
Some US observers interpreted the last minute postponement of Gorbachev's trip as a slap at Castro. But the Armenian earthquake was certainly reason enough for the postponement, and Castro accepted it as such.
Other US observers have stressed differences between Gorbachev and Castro over regional conflicts, which Gorbachev wishes to end through negotiations, while Castro, according to these same observers, prefers continued fighting.
Yet Soviet and Cuban views on this issue are in harmony. Moscow wanted a settlement in southern Africa, but so did Havana. Since 1984 Cuba has indicated its preference for a negotiated settlement that would assure Angola's security and bring about Namibian independence, thus enabling Cuba to withdraw its troops. And in Latin America, Moscow and Havana agree that conditions for armed struggle exist only in El Salvador (and perhaps Guatemala) - and even there they would prefer a negotiated settlement to continued warfare. Both also stress that conditions for ``socialist construction'' do not obtain anywhere in the hemisphere - not even in Nicaragua. In short, both Moscow and Havana accept the fact that there are not likely to be any more Cubas. This was a bitter pill for Castro to swallow, but swallow it he has.
Meanwhile, Castro's relations with the US have at least improved. An agreement on immigration matters is now in full operation. The agreement in southern Africa was reached under US sponsorship. The two sides are also discussing the issue of radio broadcasting and some more mundane consular matters.
Given Castro's more moderate posture, an inchoate US-Soviet understanding, and an improved world political climate, the prospects for easing tensions between the US and Cuba are probably better than they have been since 1976, when Gerald Ford's secret exploratory talks with the Cubans broke down over the latter's decision to go into Angola.
Central America remains a serious bone of contention and thus is one of the first issues Washington and Havana should discuss. For that matter, why not negotiate other disagreements between the US and Cuba? After 30 years, it is time to try. It was Castro the fiery young revolutionary who gave us the most problems; Castro the aging doctrinaire is more Moscow's problem than ours.