Fidel Castro's communist regime was expected to throw a tight security net around the island's tourist hotels in the wake of the clearly co- ordinated bombings. They were the latest in a series of bombs over the past five months in the capital and the Varadero resort, but the first to kill anyone.
The bombers' aim is obviously to frighten tourists from the island. Tourism has taken over from sugar exports as the number-one source of badly needed foreign currency in the wake of the break-up of the Soviet Union, Mr Castro's longtime provider.
Diplomats in Havana speculated that young military officers who are disillusioned with Mr Castro's failure to move away from Soviet-style one-party communist rule may be behind the bombings.
The authorities are likely to launch a further crackdown on political dissidents, though the dissidents have always said they want a peaceful transition to democracy. Diplomats said the bombings did not appear to be their style.
In Miami, an exile group known as Alpha 66, which holds paramilitary training sessions in the Florida Everglades, said it was not responsible for the bombings. But the group said it knew who was, and was in contact with "clandestine cells" on the island.
The group has claimed in the past to have fired at tourist beaches from small boats, but these claims appeared aimed at boosting the group's clout among anti-Castro Cuban Americans in Miami. No one on shore has reported being shot at.
The diplomats said the co-ordination of the latest bombs, which exploded within 45 minutes of one another along a seafront stretch of the once- elegant Miramar district, pointed to well-organised locals rather than infiltrators. After the bombs went off, apparently from packages left in the lobbies or off-lobby bars of the Copacabana, Triton and Chateau Miramar hotels, police and plainclothes security agents scrambled along the seafront with sniffer dogs. There were no official reports of arrests.
The bombers appeared to have scored a triple whammy in terms of discouraging visitors. The man killed in the Copacabana bar, Fabio di Celmo, 32, was an Italian businessman, based in Montreal, Canada, who had been trying to open a small business on the island. As it happens, Italy is Cuba's top source of tourists and Canada is the second. What is more, Mr Castro has been trying to encourage small foreign businesses to come to the island.
The death of Mr di Celmo may also discourage foreign tourists and businessmen from mixing with young Cuban women, known in Havana as jineteras (jockeys), who hang out in tourist hotel lobbies offering sex in return for as little as a ham and cheese sandwich. Ham and cheese are luxury items on an island where ration books are still in use.
The later explosion damaged tables at the Bodeguita del Medio in Havana's Old City, although no-one was injured. It is one of Havana's best-known tourist attractions. It was made famous by Ernest Hemingway, who used to drink rum cocktails there.