Australians would not be able to fly into the most popular entry points to the US under a plan proposed by the Trump administration.
A proposal from Homeland Security Secretary Markwayne Mullin would stop "sanctuary cities" from being able to host international airports.
A "sanctuary city" is a place where local law enforcement does not hand over undocumented migrants to federal authorities for deportation.
READ MORE: Congressman hasn't been seen for 12 weeks, won't say why
"Why are we processing international flights into the airport there?" Mullin told Fox News.
"We're currently drawing up plans to say, listen, these sanctuary cities where the local radical-left Democrats aren't allowing us to do our jobs and enforce federal laws, then we shouldn't be processing international flights into their cities either.
"Because they don't want us to enforce immigration, but they want us to process immigration at their facilities."
Such a policy would be a major inconvenience for Australians travelling to the United States.
Los Angeles and San Francisco are both considered sanctuary cities.
Most Australians flying to the US land in either of those California cities.
The only current direct route to the US mainland from Australia is to Dallas, which would not be affected.
READ MORE: Trump's handpicked candidate may cost his party their most important state
But the flight is two hours longer than Los Angeles and only flies from Sydney.
Which means if an Australian family wanted to go to Disneyland, they would need to fly 16 hours from Sydney to Dallas, then double back to Los Angeles on a three-hour flight.
Alternatively, they would have to do a stopover in Hawaii.
Direct routes to New York and Boston from Auckland would also be blocked under this policy.
The other Australian flight to North America, Sydney to Vancouver, would not be a viable stopover alternative because flights from Canada to the US would also be affected.
"Cutting off New York, LA, San Francisco, Seattle, Chicago, and other major ports of entry/departure from international flights would be the biggest self-inflicted wound to our economy since closing the Strait of Hormuz," US economist Patrick Chovanec said.
"The costs would be ridiculous.
"It's really such an impressively stupid idea, I'm kind of in awe."
Other sanctuary cities include Seattle, Chicago, Denver, New Orleans and Philadelphia.
READ MORE: Jill Biden thought Joe Biden was having a stroke during debate
NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms.
- Download the 9NEWS App here via Apple and Google Play
- Make 9News your preferred source on Google by ticking this box here
- Sign up to our breaking newsletter here
