NEW : Spy swap idea originated with the U.S. Six children of Russian agents have left the U.S. , attorneys say . All four appealed to the Russian president to free them after admitting their crimes against the Russian state , press secretary Natalia Timakova said . U.S. and Russia complete spy swap at Vienna airport . Comment:
NEW : Spy swap idea originated with the U.S. Six children of Russian agents have left the U.S. , attorneys say . U.S. and Russia complete spy swap at Vienna airport . Comment: