WASHINGTON - The U.S. faces a "heightened threat environment" from domestic extremists and people inspired by foreign terrorist groups with the approach of the holiday season, the Department of Homeland Security warned Wednesday.While DHS said it had no credible information on a specific threat, the agency warns in its latest national terrorism advisory bulletin that mass gatherings for the upcoming religious holidays could be potential targets, including from people and organizations seeking to exploit resentment over pandemic lockdowns and recent events such as the U.S.