Department of Homeland Security officials warned that the government of Iran could potentially mobilize Islamic extremists within the United States amid tensions in the Middle East.

President Donald Trump announced a ceasefire between Israel and Iran days after the United States entered the conflict by using bunker-busting bombs to eliminate three Iranian nuclear sites, but a bulletin from the Department of Homeland Security issued one day earlier warned of continued vulnerabilities.

The document said that “the ongoing Iran conflict is causing a heightened threat environment in the United States,” with the possibility of “low-level cyber attacks” against American networks by pro-Iranian hacktivists, as well as “cyber actors affiliated with the Iranian government.”

“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 bulletin cautioned.

Department of Homeland Security officials added that Iran has made repeated threats to assassinate leading American political and military leaders ever since the United States killed senior Iranian military commander Qasem Soleimani five years ago.

The agency warned that “multiple recent homeland terrorist attacks have been motivated by anti-Semitic or anti-Israel sentiment,” while the “ongoing Israel-Iran conflict could contribute” to individuals based in the United States “plotting additional attacks.”

That particular warning comes after former President Joe Biden oversaw a porous southern border during his tenure, enabling several hundred Iranian nationals to cross into the United States.

Republicans have voiced concern that the Iranians could form sleeper cells for terrorism should the United States enter into a conflict against Iran, a potential threat that has not abated with the announcement of the new ceasefire.