The Department of Homeland Security is warning of a “heightened threat environment” following U.S. strikes on Iranian nuclear sites and the deputy FBI director says the bureau's “assets are fully engaged" to prevent retaliatory violence, while local law enforcement agencies in major cities like New York say they're on high alert. No credible threats to the homeland have surfaced publicly in the days since the stealth American attack. It's also unclear what bearing a potential ceasefire announced Monday by the U.S. between Israel and Iran might have on potential threats or how lasting such an arrangement might be.