A bulletin from the National Terrorism Advisory System warns of a “heightened threat environment in the United States” following the U.S. military strikes on Iran’s nuclear sites.

The bulletin, first obtained by CBS News on Sunday morning, June 22, does not note any current specific threats, but warns that “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.”

While there are no known threats, Secretary of Homeland Security Kristi Noem said, “It is our duty to keep the nation safe and informed, especially during times of conflict.”

“The ongoing Israel-Iran conflict brings the possibility of increased threat to the homeland in the form of possible cyberattacks, acts of violence, and antisemitic hate crimes,” Noem said in a statement Sunday.

The bulletin notes that U.S. law enforcement “has disrupted multiple potentially lethal Iranian-backed plots in the United States since 2020,” and warns “the ongoing Israel-Iran conflict could also motivate violent extremists and hate crime perpetrators seeking to attack targets.”

The bulletin also warns, “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.”

The bulletin, which has now been officially shared with the public by the Department of Homeland Security, is the type of comprehensive threat assessment designed to communicate information directly to the public about threats and about “resources for how to stay safe during the heightened threat environment.”

Multiple sources tell CBS News that intelligence analysts began crafting this document earlier this month. It’s gone through many iterations, with plans to publish following any escalation in the conflict overseas or intervention by the United States.

It comes after the U.S. launched military strikes on three Iranian nuclear facilities Saturday evening, an operation that President Trump said aimed to stop “the nuclear threat posed by the world’s number one state sponsor of terror.” The president warned Iran not to retaliate and to work toward a peace deal in its war with Israel. Speaking at the White House Saturday night, Mr. Trump threatened to target other Iranian sites “if peace does not come quickly.”

Iran had previously vowed to retaliate if the U.S. joined Israel’s attack, which started June 13 with Israeli airstrikes on Iranian nuclear and military targets. More than 650 people have been killed and at least 2,000 have been wounded in Iran since then, according to a Washington-based Iranian human rights group. At least 24 have also been killed in Israel, and hundreds wounded, in Iran’s retaliatory missile and drone strikes, according to estimates from the Israeli military. The conflict has played out as Israel’s war with Hamas in Gaza continues.

“The Iranian Government has declared the United States complicit for Israel’s attack, and will almost certainly condemn direct US involvement in the conflict,” said U.S. officials in Sunday’s bulletin.

They additionally cautioned that the Israel-Iran conflict “could contribute to US-based individuals plotting additional attacks,” citing violent incidents in recent months targeting Jewish groups and institutions around the country. Federal law enforcement agencies had already issued an intelligence bulletin in early June warning that those attacks could motivate others.

Law enforcement officials in New York City said Saturday night that they were “deploying additional resources” to certain sites as a precaution. The NYPD tweeted: “We’re tracking the situation unfolding in Iran. Out of an abundance of caution, we’re deploying additional resources to religious, cultural, and diplomatic sites across NYC and coordinating with our federal partners. We’ll continue to monitor for any potential impact to NYC.”

In addition to the domestic security bulletin, the U.S. State Department issued a worldwide alert for all Americans traveling or planning to travel outside the country, noting that in light of the strikes on Iran, “there is the potential for demonstrations against U.S. citizens and interests abroad. The Department of State advises U.S. citizens worldwide to exercise increased caution.”

The alert urged U.S. nationals to check country-specific information on the U.S. State Department website before traveling to any destination.

, and contributed to this report.

The US Department of Homeland Security has warned of a heightened threat environment following America’s direct involvement in the Israel-Iran conflict. A new DHS bulletin highlights the rising risk of Iranian-linked cyber attacks on US infrastructure, including power grids, water systems, and transportation networks.

According to the bulletin, “Low-level cyber attacks against US networks by pro-Iranian hacktivists are likely, and cyber actors affiliated with the Iranian government may conduct more targeted operations.” These cyber actors are known to exploit poorly secured internet-connected devices to carry out disruptive actions, raising fears of significant impacts on civilian systems.

Threat Of Cyber And Physical Attacks In addition to digital warfare, the bulletin warns of a potential uptick in physical violence. The agency said that violent extremists in the US could become independently mobilised if Iran’s leadership issues a religious ruling, or fatwa, calling for attacks against US targets. This could lead to retaliatory violence carried out by individuals or cells sympathetic to Iran.

ALSO READ: US Fooled Iran With Decoy Strategy In Operation Midnight Hammer: Here’s How America Pulled Off 125-Aircraft Ambush | Watch There is also concern about hate crimes and extremist violence inspired by the conflict. DHS noted, “The ongoing Israel-Iran conflict could contribute to US-based individuals plotting attacks against Jewish, pro-Israel, or US government-linked targets.” Multiple recent domestic terrorist incidents have already been fueled by anti-Semitic and anti-Israel sentiment, officials said.

History Of Iranian Activity Inside US Since 2020, US law enforcement has disrupted several Iranian-backed plots on American soil, including attempts to assassinate critics of the Iranian regime. While these attempts have failed, they highlight Iran’s long-standing strategy of targeting individuals it holds responsible for the 2020 death of Qassem Soleimani, the high-ranking Iranian general killed in a US drone strike.

Iranian government-backed cyber actors have also attempted to disrupt US infrastructure in the past, focusing on energy and transportation sectors. Homeland Security now fears these efforts may intensify in the wake of recent airstrikes. The cyber threat warning comes just days after the US launched a major military operation targeting three key Iranian nuclear facilities: Fordow, Natanz, and Isfahan. Dubbed “Operation Midnight Hammer,” the strike involved B-2 stealth bombers dropping bunker-busting bombs and Tomahawk missiles launched from naval vessels.

The US government has warned of a heightened risk of cyber-attacks by Iran state-sponsored threat actors and hacktivist groups following American military strikes against Iranian targets over the weekend.

The warning was part of a National Terrorism Advisory System Bulletin issued by the US Department of Homeland Security (DHS) on June 22.

“The ongoing Iran conflict is causing a heightened threat environment in the US. 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 advisory read.

On June 21, US President Donald Trump announced to the nation that the US military had conducted air strikes on Iranian nuclear facilities, which he described as a “spectacular military success,” resulting in enrichment facilities being “completely and totally obliterated.”

The strikes came amid an ongoing conflict between Israel and Iran over the Tehran regime’s alleged nuclear ambitions.

The DHS believes that US citizens and entities are now at heightened risk of physical and cyber revenge attacks after the direct US military engagement in the conflict.

“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 targets in the Homeland,” the advisory added.

Iran’s Targeting of US Infrastructure and Politicians

The DHS advisory noted that both hacktivist and Iranian government-affiliated actors routinely target poorly secured US networks and Internet-connected devices for disruptive cyber-attacks.

Western officials have consistently warned about the threat from Iranian cyber actors to critical infrastructure in the past year.

In February 2025, the US government slammed Iran for “destabilizing and potentially escalatory” cyber-attacks on critical infrastructure, and issued sanctions against six senior officials of the Iranian Islamic Revolutionary Guard Corps Cyber-Electronic Command (IRGC-CEC) it believes were behind cyber-attacks on an Israeli manufacturer of programmable logic controllers (PLCs) used in the water sector and other critical infrastructure organizations.

In October 2024, intelligence and law enforcement agencies in Australia, Canada and the US warned about an Iran-backed year-long campaign during which hackers used brute force and other techniques to compromise organizations across multiple critical infrastructure sectors.

In the run up to the US Presidential election in November 2024, it was revealed that Iranian state-backed threat actors had targeted candidates to try and sow discord and access sensitive data.

This included the hack of one of Trump’s campaign websites.

How US Organizations Can Prepare for Iranian Cyber-Attacks

John Hultquist, chief analyst, Google Threat Intelligence Group, explained that since the October 7 terror attacks on Israel by Hamas, Iran has primarily focused its disruptive cyber-attack efforts on Israel.

With the latest US intervention increasing the likelihood of such attacks on US targets, he said it is important for individual organizations to be extra vigilant by following best practice advice.

“Iran has had mixed results with disruptive cyber-attacks and they frequently fabricate and exaggerate their effects in an effort to boost their psychological impact. We should be careful not to overestimate these incidents and inadvertently assist the actors. The impacts may still be very serious for individual enterprises, which can prepare by taking many of the same steps they would to prevent ransomware,” Hultquist noted.

He added: “Iran already targets the US with cyberespionage which they use to directly and indirectly gather geopolitical insight and surveil persons of interest. Persons and individuals associated with Iran policy are frequently targeted through organizational and personal accounts and should be on the lookout for social engineering schemes.

“Individuals are also targeted indirectly by Iranian cyberespionage against telecoms, airlines, hospitality, and other organizations who have data that can be used to identify and track persons of interest.”

UPDATE at 12:05 p.m. on June 23: 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. Live updates can be found in NBC’s live blog here.

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.

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“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. Those groups include Iranian-backed Hamas in Gaza, Hezbollah in Lebanon, the Houthis in Yemen and the Popular Front for the Liberation of Palestine, the department said.

“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,” the warning said.

In a social media post Sunday, Illinois Gov. J.B. Pritzker said he was communicating with local and federal authorities about how any potential threats could affect Illinois.

At my request, federal authorities, @ILStatePolice, and local law enforcement have kept me updated on any potential physical and cyber threats to the homeland that could affect Illinois.

We will remain vigilant and publicly communicate if there are related incidents or concerns. — Governor JB Pritzker (@GovPritzker) June 22, 2025

Pritzker also said there were no known threats to Illinois.

“I’ll continue to receive briefings as we remain vigilant to ensure the safety of Illinoisans,” he said.

Sources told NBC News Iran sent a communication to President Donald Trump in the days before Saturday night’s strikes on its nuclear facilities, threatening to activate sleeper-cell terror inside the United States if it were attacked.

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The advisory lasts for four months, and is set to expire Sept. 22, 2025, according to the bulletin.

Where things stand right now

The decision to directly involve the U.S. comes after more than a week of strikes by Israel on Iran that have moved to systematically eradicate the country’s air defenses and offensive missile capabilities, while damaging its nuclear enrichment facilities.

Early Monday, the Israeli military confirmed it struck routes leading to Iran’s Fordo enrichment facility to obstruct access.

President Trump, who has warned of additional strikes if Tehran retaliates against U.S. forces, has mused about the possibility of “regime change″ in Iran, despite administration officials earlier indicating they wanted to restart talks with Iran.

Iran’s ambassador to the International Atomic Energy Agency, Reza Najafi, condemned the “unprecedented act of aggression” against Iranian nuclear facilities by Israel and the U.S. and said that this act “delivered a fundamental and irreparable blow” to the international non-proliferation regime, including the framework of the Non-Proliferation Treaty.

Najafi was speaking to reporters at an emergency meeting of the U.N. nuclear watchdog board that addressed the situation in Iran.

He said Iran reserves its right to self-defense. “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 Islamic Republic of Iran insists its nuclear program is only for peaceful purposes. But Israel views it as an existential threat and has said its military campaign is necessary to prevent Iran from building an atomic weapon.

Last week, demonstrators in support of the IRI in Tehran protested Israel’s strikes, chanting anti-America and anti-Israel slogans while holding pictures of Iran’s supreme leader, Ayatollah Ali Khamenei.

President Trump confirmed the U.S. bombed three nuclear sites in Iran Saturday. NBC 5’s Randy Gyllenhaal has more.

‘Operation Midnight Hammer’

The United States inserted itself into Israel’s war against Iran Saturday, bombing three of the Islamic Republic’s key nuclear sites overnight in an attack it dubbed “Operation Midnight Hammer.” U.S. President Donald Trump asserted that the sites were “completely and fully obliterated,” and warned there would be additional strikes if Iran retaliates.

Israeli strikes began on June 13. Targeting Iranian military and nuclear sites, they killed several top military officials and nuclear scientists. Iran retaliated by firing hundreds of missiles and drones at Israel, some of which penetrated the country’s vaunted multi-tiered air defense system.

The US Department of Homeland Security on Sunday issued a warning of “heightened threat environment,” across the country linked to the ongoing conflict between Israel and Iran. The bulletin, effective through September 22, mentions increased risks of cyberattacks, violent extremism, and hate crimes.

In its bulletin, the ministry stated:

“The ongoing Iran conflict is causing a heightened threat environment in the United States. 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.” Story continues below this ad https://images.indianexpress.com/2020/08/1×1.png

The ministry said that Iran has a long-standing commitment to target US government officials it views as responsible for the death of an Iranian military commander killed in January 2020.

According to the bulletin, pro-Iranian hackers and cyber actors aligned with the Iranian government are likely to conduct low-level cyberattacks against US systems and internet-connected devices.

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Warnings on domestic extremism and hate crimes

The advisory flags concerns about homegrown “violent extremists” who may be inspired to act in response to global events, particularly if Iran’s leadership issues religious calls for retaliatory violence.

Recent US-based attacks fueled by anti-Semitic or anti-Israel sentiment could be precursors to more incidents, DHS warned.

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It further went on to note that militant groups like Hamas, Hezbollah, the Houthis, and the Popular Front for the Liberation of Palestine have also issued statements calling for “violence against US assets”, potentially encouraging attacks on Jewish, pro-Israel, or US government targets.

Public guidance: Stay alert, report suspicious activity

In the bulletin, the DHS listed resources “to stay safe.” It also urged public to:

Listen to local authorities and public safety officials.

Follow DHS’ cybersecurity practices to secure US networks.

Report threats or suspicious activity to local law enforcement, FBI Field Offices, or Fusion Centers

(With inputs from the official DHS bulletin)