DHS Threat to Pull CBP Puts SFO, Canada and UK Routes at Risk

Major U.S. carriers that rely on San Francisco International Airport as a global gateway are facing new uncertainty after reports indicated the Department of Homeland Security is weighing whether to reassign Customs and Border Protection officers away from airports in so-called sanctuary cities, a move that could disrupt international flights and push some Canada and United Kingdom traffic to alternate hubs in 2026.

DHS Proposal Targets CBP Staffing at Sanctuary City Gateways

Recent coverage of internal Department of Homeland Security deliberations indicates that officials are examining a controversial option: pulling or sharply reducing Customs and Border Protection staffing at airports located in jurisdictions labeled as sanctuary cities, including San Francisco International Airport. The reported discussions come against the backdrop of a protracted funding fight over immigration enforcement and border operations, and follow a period in which DHS agencies have already been operating under significant budget and staffing pressure.

According to public reporting, San Francisco International is one of several major hubs identified as potential targets for CBP reallocation, alongside other large coastal and gateway airports that sit within cities or counties with policies limiting cooperation with federal immigration authorities. While no final decision has been announced, the fact that such a move is being actively weighed has already raised alarms among airlines, airport operators and travel analysts who track the knock-on effects of staffing changes at federal inspection facilities.

Any reduction in CBP presence at an international airport would immediately affect the ability to process arriving passengers from abroad, because air carriers cannot deplane international arrivals without federal customs and immigration officers available to inspect and clear travelers. Even a partial drawdown of personnel could slow inspection lines, reduce the number of flights that can be handled in a given hour and force airlines to thin out peak arrival banks that are essential to modern hub-and-spoke networks.

For San Francisco, which functions as a key transpacific and transatlantic gateway for United Airlines and an important international outpost for Delta Air Lines and American Airlines, the proposed changes could have an impact that extends far beyond the Bay Area. Connecting traffic flowing from Asia and the Pacific into North America and onward to Europe or Canada relies on predictable processing times at customs and immigration, and any serious disruption at the federal level would ripple through airline schedules worldwide.

Why SFO Matters to Delta, United and American

San Francisco International has steadily grown into one of the most important international hubs on the U.S. West Coast, with publicly available airport data showing that United, Delta, American and other major carriers collectively operate a dense web of long haul and regional routes through the facility. United in particular treats SFO as a primary Pacific gateway, feeding traffic from smaller West Coast and Mountain West cities onto widebody services bound for Asia, Europe and Canada.

Network planners at Delta and American, while less concentrated at SFO than United, still depend on the airport for a mix of transpacific flights, code-share connections and high-yield domestic links that funnel premium passengers into their broader systems. Travel industry analyses of recent disruption events have shown that when San Francisco experiences operational strain, delays and cancellations quickly extend to other hubs such as Los Angeles, Denver, Dallas Fort Worth and Chicago, underscoring the airport’s national importance.

The role of CBP within that ecosystem is often invisible to passengers but central to airline economics. Each arriving international flight requires federal inspection capacity in the customs hall, and carriers time their schedules around assumed processing throughput. If DHS were to significantly cut CBP staffing at SFO in response to political disputes over sanctuary policies, United, Delta and American would likely need to reschedule or even relocate some long haul services in order to avoid bottlenecks, effectively reshaping how travelers move through the West Coast.

Airline financial disclosures and regulatory filings regularly warn that interruptions at major hubs, whether due to weather, construction, labor issues or government action, can have an outsized impact on profitability. A structural change to customs capacity at SFO would fall squarely into that category, particularly because the federal inspection system cannot be easily replaced or outsourced by private operators.

Scenarios for International Flight Disruption

Travel analysts examining the DHS proposal have outlined several potential scenarios for how the situation could unfold should CBP staff actually be withdrawn or substantially reduced at sanctuary city airports. The most severe would involve a near-total removal of federal inspection officers from facilities like SFO, effectively forcing airlines to suspend most or all incoming international passenger flights until alternative arrangements could be made.

A more moderate scenario, considered by some aviation observers to be more likely, would see CBP maintaining a limited presence capable of handling a smaller number of daily arrivals. Under such a model, airlines might continue to operate core transpacific and transatlantic routes but would need to cancel or retime secondary services, restrict banked arrival waves and reduce same-day connections that rely on tight minimum connection times through customs and immigration.

Operational data from recent federal staffing disruptions at U.S. airports suggests how quickly problems can cascade when security or inspection resources fall short. During past events, even small reductions in federal workforce availability have been linked to extended wait times at checkpoints, spikes in delays and localized clusters of cancellations. Applying those patterns to the far more complex federal inspection environment for international arrivals indicates that carriers at SFO could be forced into repeated last-minute schedule changes if CBP headcounts fluctuate.

In practice, Delta, United and American would likely respond by prioritizing flights with the highest revenue potential or strongest strategic value, preserving key long haul links while trimming marginal transborder or secondary international routes. That triage could leave some travelers with fewer nonstop options from the Bay Area and increase reliance on connections through other hubs.

Canada and UK Travel Could Shift in 2026

One of the most significant consequences of any CBP drawdown at San Francisco and other sanctuary city airports would be a reordering of how passengers reach Canada and the United Kingdom from the U.S. West Coast. Travel experts point to 2026 as a likely inflection point, when airlines typically plan to roll out medium term network adjustments that reflect both political developments and infrastructure constraints.

If customs capacity at SFO and similar airports becomes unreliable, carriers could redirect some Canada bound and UK bound traffic through alternative hubs with more stable federal inspection resources. On the West Coast, that might mean channeling passengers through airports in regions that maintain closer cooperation with federal immigration authorities, while for transatlantic itineraries, Midwestern and East Coast hubs could absorb flows that once moved via San Francisco.

For travelers specifically heading to Canada, another possibility involves greater use of Canadian airports with U.S. preclearance facilities, where outbound passengers complete American customs and immigration checks before departure. In such a scenario, U.S. airlines and their Canadian partners might increase capacity on select cross border routes that bypass constrained American gateways and allow smoother onward domestic connections post arrival.

United Kingdom travel patterns could shift in a similar way, with carriers boosting capacity between London and alternative U.S. hubs, then feeding West Coast travelers through domestic connections. While such routing adds time and complexity, airline scheduling models may favor it over risking long queues and missed connections at an under-resourced customs hall in San Francisco.

What Travelers Should Watch in the Months Ahead

For now, the DHS proposal to reassign CBP officers remains under consideration rather than enacted policy, and international flights at San Francisco International and other sanctuary city airports continue to operate under existing customs arrangements. However, given the political volatility surrounding immigration enforcement and the central role of federal agencies in processing international arrivals, travel industry observers recommend that passengers planning long haul trips through affected gateways in 2026 pay close attention to developments.

International travelers booked on Delta, United or American itineraries that rely on SFO as a connecting point should monitor airline schedule updates closely, particularly as carriers publish their 2026 transatlantic and transborder timetables. Changes in routings, newly added stops at alternative hubs or shifts in available departure times may serve as early signals that airlines are repositioning capacity in anticipation of possible constraints on customs and immigration processing.

Experts also note that the interplay between existing operational pressures at San Francisco, including runway work and arrival caps, and any future reduction in CBP staffing could compound disruption risk. A day that begins with weather related delays or air traffic control restrictions would leave less margin to absorb slowdowns in the federal inspection process, raising the odds of missed connections, last minute reroutes and overnight misconnects for international passengers.

With political negotiations over DHS funding and immigration policy still unresolved, the outlook for CBP staffing at sanctuary city airports remains uncertain. What is clear is that any significant shift in federal inspection resources at San Francisco International would reverberate across the route networks of Delta, United and American, and could subtly but meaningfully reshape how U.S. based travelers reach Canada and the United Kingdom in the years ahead.