Dept. of Homeland Security warns of 'heightened threat environment' following Iran strikes --Sources told NBC News Iran sent a communication to President Trump last week, threatening to activate sleeper-cell terror inside the United States if it were attacked | 23 June 2025 | UPDATE at 12:05 p.m.: According to a senior White House official, the White House and the Department of Defense are aware of, and closely monitoring, potential threats to Al Udeid Air Base in Qatar. The Department of Homeland Security on Sunday issued a new National Terrorism Advisory System Bulletin warning of a "heightened threat environment" following the U.S. strikes on nuclear facilities in Iran. "Low-level cyber attacks against US networks by pro-Iranian hacktivists are likely, and cyber actors affiliated with the Iranian government may conduct attacks against US networks," the bulletin said. It went on to say that the strikes could motivate violent extremist groups led by the Islamic Republic of Iran to "mobilize," and seek to attack targets perceived to be Jewish, pro-Israel, or linked to the US government.