The Department of Homeland Security on Sunday issued a National Terrorism Advisory Bulletin warning of a "heightened threat environment" across the United States following President Donald Trump's decision to launch coordinated military strikes on Iran's nuclear facilities over the weekend.
The bulletin, which runs through September 22, cites the possibility of cyberattacks by Iranian state-linked hackers and retaliatory action from Iranian-aligned terrorist groups such as Hezbollah, Hamas, the Houthis, and the Popular Front for the Liberation of Palestine. "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 states.
"Multiple recent Homeland terrorist attacks have been motivated by anti-Semitic or anti-Israel sentiment, and the ongoing Israel-Iran conflict could contribute to US-based individuals plotting additional attacks," it continued.
The bulletin was released within hours of the U.S. confirming it had carried out airstrikes on three Iranian nuclear sites Saturday night as part of "Operation Midnight Hammer." President Trump described the facilities as "completely and fully obliterated," warning that additional targets would be hit if Iran retaliated.
The operation followed more than a week of Israeli airstrikes aimed at dismantling Iran's missile and air defense infrastructure, which Tehran claims killed dozens of senior officials and scientists. Iran responded with massive missile and drone barrages on Israeli territory, leaving more than 24 Israelis dead and hundreds wounded, according to the Israeli military.
Iran's Supreme National Security Council released a statement Sunday calling the strikes "an unprecedented act of aggression" and vowed retaliation. Reza Najafi, Iran's ambassador to the International Atomic Energy Agency, said at an emergency meeting in Vienna: "As long as the source of the threat persists, the Islamic Republic of Iran will continue to undertake the necessary, resolute and proportionate measures to neutralize it at the time, place and manner of its own choosing."
The DHS bulletin noted that U.S. law enforcement has disrupted several Iranian-backed plots on U.S. soil since 2020. "The likelihood of violent extremists in the Homeland independently mobilizing to violence in response to the conflict would likely increase if Iranian leadership issued a religious ruling calling for retaliatory violence against the United States," it warned.
Secretary of Homeland Security Kristi Noem emphasized in a statement that while there are no specific threats currently, "It is our duty to keep the nation safe and informed, especially during times of conflict." CBS News reported that federal intelligence analysts had been preparing the bulletin for weeks in anticipation of escalated U.S. involvement.
Law enforcement officials in New York, Chicago, and Washington, D.C., said additional security was being deployed at religious and diplomatic sites. The NYPD posted: "Out of an abundance of caution, we're deploying additional resources... and coordinating with our federal partners."
Illinois Governor J.B. Pritzker confirmed coordination with local and federal law enforcement, saying, "I'll continue to receive briefings as we remain vigilant to ensure the safety of Illinoisans."
The U.S. State Department also issued a global security alert for American citizens, warning of possible demonstrations and threats to U.S. interests abroad. "The Department of State advises U.S. citizens worldwide to exercise increased caution," the alert read.
In Tehran, anti-U.S. demonstrations continued over the weekend, with protestors chanting against Israel and America while waving portraits of Supreme Leader Ayatollah Ali Khamenei. Iran has maintained that its nuclear program is peaceful, while Israel and U.S. officials say intelligence indicates an effort to develop atomic weapons.
President Trump has hinted at the possibility of "regime change" in Iran, although officials in his administration have previously signaled interest in restarting negotiations. Speaking from the White House, Trump warned: "Any retaliation by Iran against the United States of America will be met with force far greater than what was witnessed tonight."
