Qatar is employing an Italian carrier to establish a “fifth freedom” flight to the U.S., according to 3 U.S. airlines and 11 Republican senators.

Fortune reported. 

Delta, United Airlines, American Airlines, and their allies in Washington D.C. are accusing Qatar of using Air Italy as a proxy to get into the U.S. in violation of the terms of an Open Skies agreement between the U.S. and Qatar.

So-called “fifth freedoms” flights are named after the “freedoms of the air” principles. The fifth freedom sets out that an airline may fly from its home country to a second country, pick up passengers there, and then continue to a third country.