WASHINGTON — Homeland Security Secretary Markwayne Mullin is warning that foreign terrorists are joining forces with Mexican drug cartels to threaten the United States, describing an alliance he says was enabled by years of lax border enforcement. In a Fox News appearance, Mullin said terrorists have joined with the cartels and that many entered the country under the prior administration’s border policies. He claimed that more than 1,900 non-citizens have been arrested on terror-related grounds, describing them as individuals already known as terrorists.
The figures are the secretary’s own statements; independent verification of the specific numbers and of the claimed terrorist-cartel alliance has not been publicly detailed. Earlier in the year, DHS officials cited a lower figure of about 1,100 terrorism-related arrests, indicating the number has been revised upward over time.
Congress has held a series of hearings on cartel drones, tunnels and cross-border cyber activity, and lawmakers of both parties have pressed DHS for the underlying data behind its arrest figures. ## The cartel threat framework Mullin has separately told lawmakers that Mexican cartels control the entirety of Mexico’s northern border and remain a leading national security threat, pointing to cartel drone activity, fentanyl trafficking and cyber threats. The warning fits a broader administration strategy that has treated the southern border as a national-security frontier rather than solely an immigration-policy question.
Earlier in 2026, the government formally designated several major Mexican cartels, including the Sinaloa and Jalisco New Generation organisations, as foreign terrorist organisations. That designation unlocks sanctions, material-support prosecutions and expanded intelligence-sharing tools normally reserved for groups such as ISIS or al-Qaeda.
Officials argue the label lets prosecutors charge financiers and facilitators, not only smugglers caught at the line. Fentanyl remains the human core of the threat the administration cites.
The synthetic opioid, whose precursor chemicals are largely sourced from abroad and pressed into counterfeit pills by cartel networks, has driven tens of thousands of American overdose deaths annually, and Mullin has repeatedly tied cartel logistics to that toll. ## Scrutiny and pushback Analysts who track transnational crime caution that documented, operational links between recognised foreign terrorist groups and the profit-driven cartels remain thin in the public record, even as both exploit the same smuggling corridors.
Critics argue that framing immigration as a terrorism threat overstates the evidence and risks tarring large numbers of migrants with the actions of a few, while supporters say tighter border enforcement is a legitimate and overdue response to a genuine security gap. The debate over how to weigh those numbers, and how to separate genuine security threats from ordinary migration, is likely to intensify as the figures are scrutinised. The remarks come amid an aggressive nationwide immigration-enforcement campaign and underscore how central border security and the cartel threat have become to the administration’s homeland-security message heading into the fall.
