Story highlights Four Americans missionaries were released Saturday after being detained a few days ago

Not clear if this is related to detained Americans mentioned by Venezuelan President Maduro

Maduro also banned George W. Bush, Dick Cheney, others from entering Venezuela

Venezuela will now require Americans to get a visa to visit

Caracas (CNN) Venezuelan President Nicolas Maduro said Saturday an unspecified number of Americans were arrested "a few days ago" for engaging in espionage and recruitment activities.

The President said they included an American pilot of Latin American origin, arrested in the southwest border state of Táchira.

He said the pilot was found in possession of "all kinds of documents" and was being interrogated by the authorities, though he did not identify him. The Venezuelan government has made many similar claims in recent years, without ever substantiating them.

Maduro also announced Saturday a series of measures, including visa requirements for U.S. citizens and the downsizing of the U.S. Embassy in Caracas, to counteract what he called U.S. "interference" in his country.

Venezuela has in recent weeks accused the United States of being behind an alleged coup plot.

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