WASHINGTON — While they passed along no US secrets, the 10 Russian sleeper agents involved in the spy swap posed a potential threat to the US.and received "hundreds of thousands of dollars" from Russia, US Attorney General Eric Holder said."Russia considered these people as very important to their intelligence-gathering activities," he told CBS television's "Face the Nation" in an interview broadcast Sunday.RELATED:10 Russian spies plead guilty; deportedRumors of US-Russia spy exchange developHe defended the decision to allow the 10 to return to Russia in exchange for the release of four Russian prisoners accused of spying for the West because the swap presented "an opportunity to get back ... four people in whom we have a great deal of interest."Holder also sought to erase concern over the fate of the children of the Russian agents, saying they all were allowed to return to Russia "consistent with their parents wishes" or, in the case of those who were adults or nearly adults, were allowed to make their own choices of where to live."The children have all been handled, I think, in an appropriate way," he said. The seven offspring embroiled in the spy saga ranged in age from a 1-year-old to a 38-year-old architect. In most cases they were born and grew up in the United States, making them US citizens.On pending terrorism cases, Holder acknowledged "there's a real question" as to whether a terrorist suspect such as self-professed Sept. 11 mastermind Khalid Sheikh Mohammed can face the death penalty if he were to plead guilty before a military commission.Holder indicated he still favors bringing Mohammed and four alleged accomplices before civilian courts, but that has been met with opposition in Congress and elsewhere. He said no decision has been made on where the trials will be held or whether they would be civilian or military.He said one roadblock is that Congress has yet to come up with the money for the trials. "The politicization of this issue when we're dealing with ultimate national security issues is something that disturbs me a great deal," Holder said.Holder also said the closing of the Guantanamo detention camp has become more difficult "because there have been people who have changed their positions" and now refuse to provide money in Congress to relocate the detainees to an underused state prison in Illinois. He said other states have offered to take the prisoners, but did not name any states."There is no reason to believe that people held in Guantanamo cannot be held wherever we put them in the United States. Again, very safely and very effectively," Holder said.