On March 10, 2025, the House of Representatives passed the Subterranean Border Defense Act, legislation introduced by Rep. Eli Crane (R-AZ) and Rep. Lou Correa (D-CA) to strengthen congressional oversight of illicit cross-border tunnels. The bill earned strong bipartisan support with a 402-1 vote on the House floor.

Last week, Sen. Rick Scott (R-FL) introduced a companion bill in the Senate, marking key progress in the effort.

Since 1990, law enforcement has discovered more than 200 illicit tunnels along the southwest border. Transnational criminal organizations rely on these passages to smuggle drugs, weapons, currency, and people.

Earlier this year, a Homeland Security Task Force investigation uncovered a nearly 2,000-foot tunnel stretching from Tijuana to a storefront near the Otay Mesa Port of Entry and reaching a depth of 55 feet. The operation led to the seizure of more than a ton of cocaine valued at an estimated $45 million. Rep. Crane believes that as enforcement above ground drives down unlawful entries, traffickers and cartels will continue to adapt by turning to unconventional methods of evading frontline personnel.

The Subterranean Border Defense Act builds on Section 7134 of the Fiscal Year 2023 National Defense Authorization Act (NDAA). That provision directed the Commissioner of U.S. Customs and Border Protection (CBP), in coordination with the Department of Homeland Security’s Under Secretary for Science and Technology, to develop a strategic plan to counter illicit cross-border tunnel operations. Under the law, the plan was required to address the following:

• Setting risk-based criteria to prioritize the identification, breach, assessment, and remediation of tunnels
• Promoting innovative technologies to carry out that work while reducing the impact on surrounding communities
• Establishing processes for sharing tunnel location, operations, and technical information
• Providing Border Patrol sector chiefs with periodic indicators of the tunnel types found in their sectors to educate field personnel
• Assessing technology and staffing needs, including position descriptions, specialized skills, and full-time personnel levels by Border Patrol sector for counter-tunnel operations

However, the NDAA required CBP to report to Congress on the plan’s implementation only once. Rep. Crane’s bill would close this gap by converting that one-time requirement into an annual one. The legislation would direct CBP to submit a report to the House Committee on Homeland Security and the Senate Committee on Homeland Security and Governmental Affairs every year. As a result, lawmakers would receive regular updates on CBP’s efforts to counter tunnels infiltrating the United States, allowing them to craft policy based on the latest findings rather than outdated information.

“I’m grateful to Senator Rick Scott for leading the Subterranean Border Defense Act in the Senate. This legislation strengthens our deterrence posture by increasing oversight of illicit cross-border tunnels. With the Trump administration successfully halting illegal crossings at our border, it’s never been more important to block alternative routes into our homeland,” said Rep. Crane. “As Arizona’s only Member of the House Committee on Homeland Security, I will continue to do everything in my control to eliminate human trafficking, drug smuggling, and unlawful entries. This bill has already passed the House in an overwhelming bipartisan vote, and Senator Scott’s introduction of the bill in the upper chamber brings it one step closer to becoming law.”