The US government's travel ban on certain European countries is preventing travelers who have visited the continent from entering the US, even those just passing through.

Air France, Air Tahiti Nui, and French Bee all operate flights between Paris and Papeete, French Polynesia that stop in the US with a large number of European passengers who as of the past week can't enter the US.

Air Tahiti Nui and French bee have responded by rerouting flights and the latter has resulted in operating a non-stop flight from Papeete to Paris, making it the longest non-stop flight in the world.

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President Donald Trump's proclamation on Wednesday largely restricted entry into the United States for non-citizen European residents is leading to a reduction in flights across the Atlantic and airlines potentially losing a large number of passengers affected by the ban.

The ban not only prevents European travelers to enter the US but also those who pass through the US to points to reach destinations in other parts of North America, the Caribbean, South America, or Oceania.

Unlike most countries in Europe as well as neighboring Canada, the US doesn't allow for airside transfers between international flights. The regulation requires all travelers to enter the country before connecting to a flight to a third country, even if the traveler has no intention of staying in the US.

While most Europeans can enter the US under visa-waiver programs, the requirement to enter the country has ruled out American cities as transit points for those who require formal visas for entry.

Despite the US government's rules, three French airlines use the Californian cities of Los Angeles and San Francisco as stopover points for flights from Paris to Papeete, French Polynesia, a French territory in the South Pacific better known as Tahiti. Almost directly located under the near-8,500 nautical mile route, California is the ideal stopover point for the route that allows aircraft to refuel and restock before continuing the journey over the Pacific.

During the stopovers, all passengers must deplane and clear US Customs and Border Protection before returning to the aircraft for the second and final leg either to Paris or Papeete, depending on the direction of flight. Even though the entirety of their stay in the US will be at the airport, all the same formalities apply.

Three airlines operate flights between France and Tahiti including Air France, Air Tahiti Nui, and French Bee. All three have had their operations on the route impacted by President Trump's travel ban, each taking a different approach with some more drastic than others.

Here's how French airlines are responding to the crisis.