US officials said the 10 agents expelled from the United States on Thursday in exchange for four Russian prisoners had signed plea agreements forfeiting their US properties and bank accounts, as well as the right to sell their stories in any form.
"That is a not uncommon provision ... in cases like this that enjoy a certain notoriety," said one senior administration official, after Washington and Moscow agreed one of their biggest spy swaps since the end of the Cold War. "It is not something unique to this case."
Officials were cautious with information about the exchange that defused a potential diplomatic clash just as ties between the two countries were warming, Telegraph.co.uk reports.
The Associated Press said that a maroon-and-white Boeing 767-200 chartered jet carrying the 10 agents from New York taxied to a halt in Vienna behind a Russian Emergencies Ministry plane that was believed to be carrying the freed Russians.
The 10 accused, U.S.-based spies pleaded guilty in a Manhattan courtroom Thursday to acting as unregistered foreign agents for Russia, a charge well short of espionage. They had endured only a few days of jail time since their arrests in the United States last month; in prior cases, spies spent years behind bars before being exchanged.
Russian small missile ships - the Grad Sviyazhsk and the Great Ustyug - set off for a mission to the Mediterranean Sea