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United States officials are sounding the alarm regarding the threat of terror-backed sleeper cells within the country just hours after President Donald Trump successfully ordered the elimination of key nuclear facilities within Iran.

Just hours after Trump addressed the nation on U.S. military strikes on the Iranian nuclear sites, the DHS released a new memo sounding the alarm to a “heightened threat environment in the United States.”

The bulletin from the National Terrorism Advisory System did not cite any specific threats but comes as Iranian officials have threatened retaliation.

TRUMP ADDRESSES NATION ON ‘SPECTACULAR MILITARY SUCCESS’ OF US STRIKES ON IRANIAN NUCLEAR FACILITIES

With the regime’s nuclear program severely set back, and its infrastructure bombarded during Israel’s operation, one former FBI boss told Fox News Digital that Iran and its proxies could resort to their original tactic — terrorism. And the border crisis under the Biden administration only exacerbates the threat of terror cells in the U.S. activating to harm Americans at home.

“The likelihood of violent extremists in the Homeland independently mobilizing to violence in response to the conflict would likely increase if the Iranian leadership issued a religious ruling calling for retaliatory violence against targets in the Homeland,” the bulletin states.

“It is our duty to keep the nation safe and informed, especially during times of conflict,” the Department of Homeland Security said in a statement to Fox News Digital. “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.”

The bulletin points to law enforcement within the U.S. disrupting “multiple potentially lethal Iranian-backed plots” since 2020, while noting the Iranian government’s unsuccessful attempts to target critics of its regime.

MISDIRECTION AND ‘DECEPTION’ LIKELY KEY IN TRUMP ADMIN’S SURPRISE IRAN STRIKE

Iran previously vowed to retaliate if the U.S. became involved in Israel’s attack, which began after Israeli airstrikes targeted Iranian military and nuclear facilities on June 13. Prior to the attack, Trump issued a warning to Iran against retaliating, while encouraging the country’s leaders to come to a peace deal with Israel. Immediately following the strikes, Trump vowed to target additional sites within Iran “if peace does not come quickly.”

The advisory comes after Trump ordered military strikes on Iran’s key nuclear facilities in what officials are calling “Operation Midnight Hammer,” prompting law enforcement to be on high alert regarding the threat of foreign adversary operatives conducting an attack on U.S. soil, with thousands of Iranian nationals previously crossing over the border.

“Because of the open borders, we are at a serious catch-up phase” Former FBI assistant director Chris Swecker told Fox News Digital. “We don’t know where those thousand Iranians are and who knows how many others got across the border. We missed an opportunity when they caught and released those thousand. We missed the opportunity to gather intel by interviewing them and thoroughly vetting them. We just simply let them go, which is gross negligence on the part of the Biden administration.”

U.S. Customs and Border Protection did not immediately respond to Fox News Digital’s request for comment.

IRAN THREATENS TO HIT US BASES IN THE MIDDLE EAST: WHAT IS THE THREAT LEVEL?

“We don’t know where those thousand Iranians are and who knows how many others got across the border.”

Over 1,200 Iranian nationals reportedly entered the U.S. during former President Joe Biden’s time in office, White House border czar Tom Homan told Maria Bartiromo on “Sunday Morning Futures.” The threat of foreign nationals flowing into the U.S. raises concerns regarding possible domestic sleeper cells driven by foreign terrorist organizations, according to national security experts.

“The challenge that the United States has had after a very long period of time, [is that] we had an open border,” Michael Balboni, former Homeland Security advisor for New York state and a cybersecurity expert, told Fox News Digital. “Tens of millions of people came across and we don’t know who they are, where they came from, what their capabilities are or their intentions.”

Swecker indicated the FBI has primarily focused its attention on homegrown attackers as foreign adversaries flowed into the country.

ISRAEL’S ACTIONS AGAINST IRAN CREATE STRATEGIC OPPORTUNITY FOR US IN NUCLEAR TALKS, EXPERTS SAY

“There’s a certain population of Iranians in the U.S. that we know about, but there’s thousands and thousands that we don’t know about because of the open border situation,” Swecker said. “The Bureau was concentrating their resources on so-called domestic terrorists like white supremacists and right-wing extremists, and calling them the most serious terrorist threat to this country when it was absolutely the international terrorists that should have been the focus of the bureau’s efforts.”

The FBI declined Fox News Digital’s request for comment.

The possibility of foreign cells carrying out a domestic terror plot was pushed into the national spotlight last year after federal prosecutors announced a member of Iran’s Islamic Revolutionary Guard Corps and two U.S.-nationals were arrested for allegedly plotting to murder then-President-elect Trump and a U.S. citizen critical of the Iranian regime.

SATELLITE IMAGE SHOWS FORDOW NUCLEAR FACILITY AFTER MASSIVE BOMB STRIKE

“The Iranians have shown a pretty good capability in terms of their intelligence apparatus and their operatives being able to work clandestinely,” Balboni said. “They are fairly sophisticated when it comes to that, very determined. The question is how many are in the country and the answer is we don’t know.”

The U.S. possesses a wide range of attractive targets, with national security concerns spiking after Trump ordered the assassination of Iranian General Qasem Soleimani in January 2020.

“They’re not going to quit,” Swecker said. “They will never quit. And this was the right thing to do to take out their nuclear capabilities.”

EXPERTS CONFIDENT IRAN’S NUCLEAR PROGRAM IS ‘NO LONGER’ AFTER MASSIVE US STRIKE

Additionally, critical infrastructure within major cities remains a prime spot for cells to carry out destructive terror plots, with Iranian officials likely turning to proxy groups to sow fear within the population.

“Electrical grids, perhaps medical facilities, transportation hubs,” Balboni said. “Those types of things that have been a part of the playbook when you have these insurgencies that happened within the nation.”

Balboni points to instances of terror cells conducting pre-operational surveillance within the U.S., adding satellite mapping websites provide adversaries with a birds-eye view of key infrastructure.

A FULL BREAKDOWN OF OPERATION MIDNIGHT HAMMER, THE ‘LARGEST B-2 OPERATIONAL STRIKE IN US HISTORY’

“Law enforcement and security personnel are really focused now on trying to prevent anything from happening,” Balboni told Fox News Digital. “But the problem is if you’ve had tens of millions of people come across the border, you really don’t know where they are and what their capabilities are.”

As tensions between the Middle East and the U.S. continue to spiral toward a breaking point, the National Terrorism Advisory System warns of U.S.-based individuals “plotting additional attacks” against pro-Israel targets, and U.S. government and military officials.

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“This is a time for calm, professionalism, information sharing and heightened awareness,” Balboni said. “This will not be the first time we face a challenge like this. But certainly because of the hostilities, there is a heightened fear, concern and awareness that these types of attacks could happen in the United States.”

The U.S. Department of Homeland Security (DHS) has issued a new National Terrorism Advisory System (NTAS) bulletin, warning of a “heightened threat environment” across the United States following escalating conflict between the U.S. and Iran.

The bulletin, effective through September 22, 2025, cites increased risk of cyberattacks and potential retaliatory violence on U.S. soil. It comes in the wake of recent U.S. military strikes on Iranian nuclear facilities, which have further strained international tensions.

Key Threats Identified

Cyberattacks by pro-Iranian hackers and Iran-affiliated cyber actors targeting U.S. networks are “likely.”

and Iran-affiliated cyber actors targeting U.S. networks are “likely.” The Iranian regime may attempt to retaliate against U.S. officials , particularly in response to the 2020 drone strike that killed Qassem Soleimani.

, particularly in response to the 2020 drone strike that killed Qassem Soleimani. Violent extremists in the Homeland could be inspired by the conflict, especially if Iran issues a formal call for retaliatory action.

could be inspired by the conflict, especially if Iran issues a formal call for retaliatory action. The bulletin notes a potential increase in antisemitic or anti-Israel attacks from U.S.-based individuals.

Ongoing Concerns

Since 2020, U.S. authorities have disrupted several Iranian-backed plots. DHS highlights previous attempts to target dissidents and critics of the regime living in the U.S., as well as potential use of religious rulings by Iran’s leadership to incite violence.

Terror-linked groups such as HAMAS, Hizballah, the Houthis, and others have released statements threatening U.S. interests, further exacerbating the threat level.

DHS Safety Recommendations

Citizens are urged to:

Stay informed through local authorities and public safety officials .

. Follow cybersecurity best practices as outlined by the Cybersecurity and Infrastructure Security Agency (CISA) .

. Report suspicious activity to law enforcement via 911, FBI Field Offices, or the Nationwide SAR Initiative (NSI).

The advisory reiterates the government’s longstanding message: “If You See Something, Say Something®.”

For more information, visit DHS.gov/advisories.

The National Terrorism Advisory System has sent out a bulletin warning of a “heightened threat environment in the United States” following the U.S. military strikes on Iran’s nuclear sites.

CBS News, which obtained the bulletin on Sunday morning, 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.”

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.”

CBS News attributed many sources in reporting that intelligence analysts began assembling this document earlier this month.

It’s gone through many versions, with plans to publish following any escalation in the conflict overseas or intervention by the United States, according to CBS News.

The bulletin comes this weekend after the U.S. launched military strikes on three Iranian nuclear facilities, an operation that President Trump said aimed to stop “the nuclear threat posed by the world’s number one state sponsor of terror.”

Meanwhile, Secretary of State Marco Rubio said on Sunday that the United States currently has no military operation planned against Iran but left the door open for future strikes if it does not show a meaningful effort to make peace.

“We have other targets that we could hit, but we achieved our objective,” Rubio said in an interview on CBS News’s “Face the Nation.”

Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources.

Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content.

The U.S. Department of Homeland Security (DHS) warned on Sunday that the “ongoing Iran conflict is causing a heightened threat environment in the United States,” in a post on the National Terrorism Advisory System Bulletin.

The post comes hours after Washington struck three key nuclear facilities in Iran Saturday night.

Why It Matters

Iran is weighing its response to U.S. airstrikes on three of its nuclear sites—Isfahan, Fordow and Natanz—carried out Saturday night. Possible options include, but are not limited to retaliatory strikes, diplomatic engagement or leveraging its control over the strategic Strait of Hormuz.

The U.S. and Iran have had an over four-decade long strained, distrusting relationship. During President Donald Trump’s first administration, tensions were notably high after Trump withdrew from the Joint Comprehensive Plan of Action (JCPOA), known as the Iran Nuclear Deal, and the U.S. killed Iranian General Qasem Soleimani, leader of the Quds Force.

What To Know

In the summary, the DHS warned 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.” The National Security Agency (NSA) and other U.S. security agencies have long warned of cyberattacks.

The notice, which was issued on June 22 and is set to expire on September 22, said, “Iran also has a long-standing commitment to target US Government officials it views as responsible for the death of an Iranian military commander killed.”

The comment is in reference to the U.S.’s take out of Soleimani, however, the remark is in contrast to Trump’s decision to revoke the security clearance of several people involved in the organization and execution of the strike, including former national security adviser John Bolton and former Secretary of State Mike Pompeo.

“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 department said.

DHS has issued information on resources to stay safe, outlining who to call and how to report concerns.

The “threat summary” comes after “US law enforcement has disrupted multiple potentially lethal Iranian-backed plots in the United States since 2020.” The FBI and Justice Department have worked together to bring forward several charges on Iranian nationals seeking to carry out alleged murder and assassination plots on U.S. soil, including one against Bolton.

In a tit-for-tat exchange over five years ago, the U.S. designated the Islamic Revolutionary Guards Corps (IRGC) a terrorist group, and in response Iran’s Supreme National Security Council designated the United States Central Command (CENTCOM) as a terrorist and labeled the U.S. as a “supporter of terrorism.” In addition to labels, the U.S. has also levied a slew of sanctions on the country over the years.

The warning notes that regional armed groups, some identified as terrorist organizations by the U.S., “have called for violence against US assets and personnel in the Middle East because of Israel’s attack [on Iran].” Israel had been striking Iran for nine days before the U.S. formally got involved.

The State Department’s Consular Affairs posted a “worldwide caution” security alert on Sunday, warning that “the conflict between Israel and Iran has resulted in disruptions to travel and periodic closure of airspace across the Middle East.”

The alert continued, “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.”

Department of Homeland Security police officers stand outside the Federal Courthouse on June 13 in Nashville, Tennesse. Department of Homeland Security police officers stand outside the Federal Courthouse on June 13 in Nashville, Tennesse. AP Photo/George Walker IV

What People Are Saying

Former FBI Director Christopher Wray said in a statement on the FBI website dedicated to the “Iran Threat”: “The conduct charged shows how far Iranian actors are willing to go to silence critics, even attempting to assassinate a U.S. citizen on American soil. We are determined to safeguard the rights of all Americans from the oppressive reach of hostile regimes.”

Iranian President Masoud Pezeshkian: “Our nation will not knee down in the face of bullying and oppression. It is natural that it will respond to the aggression proportionately. It was the US that attacked us. What would you do if you were us? Naturally, they must receive a response for their aggression.”

President Donald Trump on Truth Social on Saturday: “ANY RETALIATION BY IRAN AGAINST THE UNITED STATES OF AMERICA WILL BE MET WITH FORCE FAR GREATER THAN WHAT WAS WITNESSED TONIGHT.”

Defense Secretary Pete Hegseth said during Sunday morning’s press conference: “The operation President Trump planned was bold and it was brilliant, showing the world that American deterrence is back when this president speaks, the world should listen and the U.S. military, we can back it up. The most powerful military the world has ever known. No other country on planet Earth could have conducted the operation that the chairman is going to outline this morning.”

Iranian Foreign Minister Seyed Abbas Araghchi on X, formerly Twitter, on Sunday: “The United States, a permanent member of the United Nations Security Council, has committed a grave violation of the UN Charter, international law and the NPT by attacking Iran’s peaceful nuclear installations. The events this morning are outrageous and will have everlasting consequences. Each and every member of the UN must be alarmed over this extremely dangerous, lawless and criminal behavior. In accordance with the UN Charter and its provisions allowing a legitimate response in self-defense, Iran reserves all options to defend its sovereignty, interest, and people.”

What Happens Next?

During a Sunday phone call with French President Emmanuel Macron, Iranian President Masoud Pezeshkian said that the U.S. must “receive a response to their aggression,” according to Iran’s official news agency, IRNA, as reported by The Times of Israel.

Update 6/22/25, 6:19 p.m. ET: This article has been updated with additional information.

Update 6/22/25, 4:21 p.m. ET: This article has been updated with additional information.

The alert says low-level cyberattacks, plots against U.S. officials, and extremist violence at home could all rise in the coming weeks as tensions overseas continue.

“The ongoing Iran conflict is causing a heightened threat environment in the United States,” the Department of Homeland Security said in the bulletin, which remains active through Sept. 22.

The warning has prompted New York Gov. Kathy Hochul to take immediate action.

“My top priority is the safety of New Yorkers,” Hochul said Sunday. “Last night, following President Trump’s announcement, I convened my senior public safety team and spoke with colleagues in the federal and local government.”

“We are not aware of any specific or credible threat to New Yorkers. However, given New York’s distinctive global profile, we are taking this situation extraordinarily seriously,” she said.

Gov. Hochul said she has remained in close contact with State Police Superintendent Steven G. James, along with homeland security, counterterrorism, and cybersecurity experts.

“All State agencies, utilities and other critical infrastructure facilities are on high alert to monitor for any possible disturbances,” she said.

“As a precaution, the MTA and Port Authority have activated counterterrorism protections in partnership with local law enforcement. The State Police will continue safety patrols outside houses of worship and other at-risk sites — efforts that have been underway since the onset of this crisis.”

“We have some of America’s largest Jewish and Muslim communities, and many have loved ones in the region. As we work to keep New Yorkers safe, we pray for the safety of our American troops, for speedy deescalation of this conflict, and for durable peace in the region,” Hochul said.

⚠️ What the DHS Bulletin Says

The Department of Homeland Security says the threat includes:

Cyberattacks by pro-Iranian hacktivists or Iranian government-affiliated actors

Plots by violent extremists motivated by anti-Semitic or anti-Israel sentiment

Possible retaliation against U.S. government officials for past strikes

Attempts to target critics of the Iranian regime in the U.S.

Terrorist propaganda calling for violence against U.S. assets in the Middle East

“The conflict could also motivate violent extremists and hate crime perpetrators seeking to attack targets perceived to be Jewish, pro-Israel, or linked to the US government or military in the Homeland,” the bulletin says.

Officials warn that if Iranian leaders issue a religious ruling calling for violence, it could further increase the risk of attacks on U.S. soil.

Federal authorities are urging the public to stay vigilant:

Call 911 in case of emergency

Report threats to local police, FBI, or a regional Fusion Center

Visit DHS’s Cybersecurity and Infrastructure Security Agency (CISA) for online safety guidance

“If You See Something, Say Something®,” the bulletin reminds Americans.

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