WORLD REPORT EXTRA: The Coup and Beyond : World View : Holding Out for Hammer and Sickle : There are still several orthodox Communist states in the world. Their reaction to the sudden fall--and return--of Mikhail Gorbachev. : CUBA : ‘Option Zero’ in Havana

When President Fidel Castro began uttering the term “option zero” last spring to describe a hypothetical cutoff of all Soviet aid and commerce to his country, Cubans panicked. The state-controlled press, after dutifully reporting on drills by factory workers and army units to operate without petroleum, was quickly ordered to drop the subject.

After a few months of uneasy calm, “option zero” came terrifyingly close to reality this week as a right-wing faction in Moscow overthrew President Mikhail S. Gorbachev and the Soviet Union hovered on the brink of civil conflict.

“A lot of people who heard the news Sunday night didn’t sleep, worrying where on Earth Cuba was going to get its oil and its grain,” said Enrique Lopez Oliva, a Havana University history professor.

So dependent is Cuba on the Soviet economy that the collapse of the coup and Gorbachev’s quick return to power Wednesday brought an audible sigh of relief here. But with it came a new shudder of insecurity: Will the defeat of orthodox Communists in the Soviet bureaucracy, army and KGB end three decades of pampered treatment for Castro’s Communist revolution?

“The regime has been very nervous these past few days,” said a Western diplomat in Havana. “They were hoping the coup would succeed because (it was) led by men who want to preserve a strategic relationship to Cuba and, with it, a special economic relationship. But no one in the Cuban leadership had much confidence in that outcome.”

In its only formal statement of the Soviet upheaval, issued Tuesday when the hard-liners were still in power, Havana professed neutrality in a conflict that is “not Cuba’s to judge.” It accused Western news agencies of “inciting division and conflict” in the Soviet Union by highlighting popular resistance to the coup. And it expressed hope that the Soviet Union “will stay united, wielding international influence as an indispensable counterweight” to the United States.

The 65-year-old Castro, dependent upon Moscow throughout a 30-year-old U.S. trade embargo against his country, has made no secret of his distaste for Gorbachev’s democratic and economic reforms. Last month, when Soviet Communists adopted a platform shedding decades of Marxist-Leninist dogma, the Cuban leader declared, “In this revolution there will be no changes of name or ideas.”

Thus disqualifying Cuba from significant help from the West, Castro has been forced to adapt to the more decentralized, profit-oriented Soviet economy, trying to assure the supply of 70% of Cuba’s imports and 90% of its petroleum.

Under a union treaty that was opposed by the Soviet hard-liners and is now expected to be signed, the Soviet republics will become more autonomous, and Cuba will have to make separate trade deals with each. Elected leaders such as Boris N. Yeltsin, the Russian Republic president, are certain to face popular pressure to pay more attention to economic woes at home and less to those in Cuba, diplomats in Havana say.