Moscow has said the arrest by the United States of a Russian man on computer-hacking charges amounts to the "kidnapping of a Russian citizen."
Roman Seleznyov, 30, was arrested on July 5 in the Maldives by the U.S. Secret Service and transported to Guam.
He is accused of hacking U.S. retail computer systems to steal thousands of credit-card numbers.
The Russian Foreign Ministry said on July 8 that "we consider this as the latest unfriendly move from Washington" and asked for "coherent explanations about the incident."
Seleznyov is the son of Russian Duma deputy Valery Seleznyov.
ITAR-TASS quoted Seleznyov as confirming the arrest.
Seleznyov was indicted in Washington state in March 2011 on charges including bank fraud, causing damage to a protected computer, obtaining information from a protected computer, and aggravated identity theft.
Based on reporting by Interfax, ITAR-TASS, Reuters, Bloomberg, and AP