40 jihadis who joined ISIS return to U.S.Dozens of American jihadis who fought in the war in Iraq and Syria have returned to the United States equipped with the training they used fighting either for or against ISIS, according to one federal official. And their activities are being monitored. Or not. “You can’t know everything,” Homeland Security Secretary Jeh Johnson said in a recent interview. It was in a televised chat with Lesley Stahl of “60 Minutes” that he admitted there may not be as much oversight of those who trained and fought with terrorists as some people would like. Stahl asked: “As I understand it, of the 180 Americans who have gone overseas to fight in Iraq and Syria, 40 have come back. I assume you’re keeping close tabs on those 40?”  Said Johnson: “We have in fact kept close tabs on those who we believe have left and those who’ve come back. A number have been arrested or investigated and we have systems in place to track these individuals. “But you can’t know everything.” FULL REPORT