(NewsNation) — With the United States on high alert for possible retaliation from Iran, the United States Immigration and Customs Enforcement has shifted to arresting Iranian nationals.

The Department of Homeland Security over the weekend said ICE agents arrested 11 individuals who were illegally living in the country.

“Under @Sec_Noem, DHS has identified and arrested known or suspected terrorists and violent extremists that illegally entered this country, came in through Biden’s fraudulent parole programs or otherwise,” Homeland Security posted on X. “We have been saying we are getting the worst of the worst out—and we are. We don’t wait until a military operation to execute; we proactively deliver on President Trump’s mandate to secure the homeland.”

Since the weekend, DHS has warned Americans of a “heightened threat environment” following U.S. strikes on Iranian nuclear sites.

Deputy FBI director Dan Bongino added the bureau’s “assets are fully engaged” to prevent retaliatory violence, while local law enforcement agencies in major cities like New York say they’re on high alert.

In addition, the State Department also issued a “worldwide caution” security alert almost 24 hours after the attacks.

“The conflict between Israel and Iran has resulted in disruptions to travel and periodic closure of airspace across the Middle East,” the State Department said. ”There is the potential for demonstrations against U.S. citizens and interests abroad.”

No credible threats to the U.S. have surfaced publicly since the attack.