If the U.S. Department of Homeland Security proceeds with a new proposal, some customs and border enforcement personnel could be withdrawn from major U.S. airports located in "sanctuary cities." Aviation industry experts warn that this would not only lengthen entry processes but could also force airlines to temporarily reroute flights, rearrange ground support, and disrupt international passenger and cargo networks.
Flights may be forced to divert.
At the heart of this plan is to reduce the number of customs and border protection personnel at some airports. If international gateway airports such as New York's JFK, Los Angeles' LAX, or Newark are affected, airlines will have to divert their scheduled inbound flights to other airports that can handle international arrivals.
The problem is that alternative airports are already busy. Airlines not only have to rearrange gates and slots, but also adjust check-in, baggage, cleaning, catering, and ground service teams simultaneously. For multi-day transoceanic routes, temporary diversions will quickly amplify operational pressure.
The accommodation of transit passengers is more complicated.

Changing the landing point is not just about changing the destination. Many passengers' final destination is not the city of entry, and once the flight lands at an alternative hub, subsequent connections become complicated.
If the alternative airport does not have direct flights to the destination, the airline may need to rebook its own flights or even coordinate with other airlines. If flights for the day are full, passenger delays, accommodation costs, and additional transportation costs will all increase.
- Changes in the port of entry will affect subsequent transit arrangements.
- When popular hubs are full, rescheduling options are limited.
- Passenger accommodation costs may increase significantly.
Industry experts say it will impact aviation and tourism.
Airlines for America, an American aviation industry organization, said that cutting customs and border protection personnel at major U.S. airports would have a serious impact on the aviation and tourism industries and affect international freight.
Aviation consultancy AeroDynamic Advisory points out that passengers complete customs procedures at the port of entry, not at their final destination. This means that restricting major entry points in blue states will not only have local effects but will also spread to more states along the national flight network.
The U.S. Travel Association also believes that such practices may have a greater impact on U.S. citizens returning from overseas than on international visitors.
The proposal still lacks specific implementation details.
U.S. Homeland Security Secretary Markwayne Mullin has stated multiple times in recent months that the federal government should reassess whether to continue maintaining resource allocation at airports in some "sanctuary cities" if they do not cooperate with federal immigration enforcement. He also indicated that the department needs to reallocate federal personnel to certain areas.
However, the Department of Homeland Security has not yet specified which airports will be included, the scale of the relocation, or a concrete timeline for implementation. U.S. Transportation Secretary Sean Duffy previously stated at a congressional hearing that restricting travel based on political affiliation would be "a bad idea."

Airport capacity is also a limitation.
Even if the policy is implemented, airlines will find it difficult to quickly relocate all their international flights to other cities. Some airports in non-"sanctuary cities" have limited capacity, and their runways, terminals, customs facilities, and ground support capabilities may not be sufficient to handle additional international flights.
In Texas, for example, Dallas-Fort Worth, Houston, Austin, and San Antonio could theoretically handle more traffic, but not every airport is suitable for all long-haul wide-body aircraft. Expanding terminals, aircraft stands, and customs facilities often requires years and significant investment.
Given the existing staff shortages in the U.S. air traffic control and security systems, concentrating more international flights at a few busy airports could further increase queuing times and the risk of flight delays.









