U.S. law enforcement agencies have intensified their monitoring of operatives linked to Iran within the country, according to several sources who spoke with CBS News. Officials say FBI Director Kash Patel has ramped up surveillance efforts targeting suspected Hezbollah-affiliated sleeper cells operating domestically. Hezbollah, which receives support from Iran, is designated as a foreign terrorist organization by the U.S. government.

According to the CBS report, the FBI and the White House have both declined to comment on the matter thus far. Concerns over Iranian-linked threats within the U.S. have persisted among current and former officials, especially following the U.S.-ordered killing of Iranian General Qasem Soleimani in January 2020 under then-President Donald Trump.

Federal prosecutors announced late last year that an operative with Iran’s Islamic Revolutionary Guard Corps (IRGC), along with two individuals based in the U.S., faced charges for allegedly plotting to surveil and assassinate individuals critical of the Iranian regime. The IRGC operative reportedly told investigators that unnamed officials within the IRGC had pressured him to develop plans for an attack on Trump.

For many years, American intelligence and law enforcement agencies have expressed concern over Iran’s capability to orchestrate or inspire attacks on U.S. soil—fears that have grown more urgent since Soleimani’s death. Agencies such as the FBI and Department of Homeland Security have allocated substantial resources to confront this threat.

Authorities have identified several potential high-profile targets. In past cases, individuals have been prosecuted for attempting to assassinate critics of the Iranian government, including former National Security Adviser John Bolton and Iranian American journalist Masih Alinejad. Bolton, a vocal critic of Tehran, received Secret Service protection in 2021, though that protection was rescinded by President Trump earlier this year.

Trump is weighing a potential military strike on Iran’s uranium enrichment facility in Fordo, possibly aligning with Israel’s ongoing campaign against Iranian nuclear and military infrastructure. White House Press Secretary Karoline Leavitt stated on Thursday that the president is expected to make a decision within two weeks, noting there is “a substantial chance of negotiation that may or may not take place” with Iran.

In response, Iran has warned of retaliation if the United States proceeds with any military action.