Miami ? Under growing international pressure, U.S. authorities Tuesday seized a Cuban exile accused by Fidel Castro’s government of masterminding a 1976 airliner bombing that killed 73 people. He had been seeking asylum in the United States.

Luis Posada Carriles, a 77-year-old former CIA operative and Venezuelan security official, was taken into custody by U.S. immigration authorities, the Homeland Security Department said.

The department did not say what it planned to do with Posada. Venezuela has asked for his extradition, and Cuba has asked that he be sent to Venezuela for retrial in the bombing or go before an international tribunal.

Posada escaped from prison in Venezuela in 1985 while awaiting a prosecutor’s appeal of his second acquittal in the bombing of a Cuban jetliner near Barbados. His whereabouts had been unknown until he surfaced in Miami in March and sent word that he was seeking asylum.

The request brought protests from Cuba and put the United States in an awkward position, given the war against terror.Castro has demanded Posada’s arrest by U.S. authorities for his alleged role in the airliner bombing and other anti-Castro violence. That demand was echoed by thousands in protests in Havana on Tuesday.

“The majority of Americans would never be in favor of harboring a terrorist,” said Wayne Smith, a former U.S. envoy to Cuba. If the United States were to grant asylum, he added, “we will be seen as hypocrites and as being against terrorism only when is suits our purposes.”