NEW : Spy swap idea originated with the U.S. They then boarded a U.S.-chartered flight accompanied by U.S. marshals , a federal law enforcement source said . Six children of Russian agents have left the U.S. , attorneys say . Russia and Moscow complete spy swap at U.S. airport . Moscow airport confirms plane landed with Six Russian agents aboard .
NEW : Spy swap idea originated with the U.S. Six children of Russian agents have left the U.S. , attorneys say . Russia and Moscow complete spy swap at U.S. airport . Moscow airport confirms plane landed with Six Russian agents aboard .