Context:

Escalating border interceptions of Iranian nationals have heightened U.S. anxiety about potential sleeper cells and retaliation amid recent U.S. and Israeli strikes on Iran. Authorities warn of unknown numbers entering undetected, while assessments indicate Iran poses a persistent threat of targeted actions and possible cyber retaliation, though a large-scale physical attack remains unlikely. The discussion is tempered by incomplete public records about operational networks, even as lawmakers urge vigilance. The outlook centers on enhanced monitoring, continued intelligence briefings, and preparedness for various threat vectors as tensions persist. Momentum remains fragile as authorities balance risk awareness with limited public evidence of a ready-to-operate sleeper-cell network.

Dive Deeper:

• U.S. officials have flagged growing concern about sleeper-cell risks after intercepting roughly 1,500 Iranian nationals at the southern border under the previous administration, with questions about how many more may have entered undetected.

• A Department of Homeland Security intelligence assessment described Iran and its proxies as probably posing a persistent threat of targeted attacks in the United States, while deeming a large-scale physical assault unlikely and citing cyber retaliation as the near-term risk.

• Encrypted transmissions believed to be Iranian in origin were highlighted in a federal alert reviewed by ABC News as potentially intended to activate prepositioned assets outside Iran, though no specific operational threat location was identified.

• Public records show 1,504 Iranian nationals apprehended between FY2021 and FY2024, with about 700 released into the U.S. while awaiting immigration hearings; separate CBP figures indicate around 1,650 encounters from 2022 through 2025.

• There have been prosecutions linking IRGC-directed activities to plots on U.S. soil, including a 2024 case involving a murder-for-hire surveillance operation against an Iranian dissident in New York and a 2023 case involving an operative aimed at political assassinations.

• Bipartisan lawmakers emphasize vigilance, noting safety challenges and underscoring that even a single insider threat could have serious consequences, while acknowledging gaps in public evidence about a broad, active sleeper-cell network.