By Tyler Clifford (Reuters) – Election officials in the United States have been alerted to safe-proof their voting systems and be vigilant about political violence amid a “very complex threat environment,” top U.S. cybersecurity official Jen Easterly said on Sunday in the wake of an attack on the husband of a leading Democratic lawmaker last week. Easterly, the director of the U.S. Cybersecurity and Infrastructure Security Agency (CISA), in an appearance on CBS “Face the Nation” said the agency is concerned about a range of threats, including cyber, insider, physical and disinformation even as…