(Reuters) - The U.S. government should not restrict Qatar Airways or Air Italy from flying to the United States because it may lead to the unraveling of other aviation agreements around the world, three U.S. airlines said in a letter to officials on Wednesday.

FILE PHOTO: A Qatar Airways Boeing 7878 Dreamliner airplane is pictured at Leonardo da Vinci-Fiumicino Airport in Rome, Italy, March 30, 2019. REUTERS/Alberto Lingria/File Photo

Washington is scrutinizing state-owned Qatar Airways’ acquisition of 49 percent of Air Italy, which has been flying to U.S. destinations since June, a deal that U.S. lawmakers say may have violated a commitment by the Gulf airline not to add new flights to the domestic market.

But in a letter to Secretary of State Mike Pompeo and Secretary of Transportation Elaine Chao, JetBlue Airways Corp and cargo carriers FedEx Corp and Atlas Air Worldwide Holdings Inc said restricting the rights of Qatar Airways and Air Italy could lead to retaliation against U.S. carriers.

“For JetBlue, who just announced its intention to begin service to London from New York City and Boston starting in 2021, the possibility of retaliation could have a devastating impact on the ability to obtain authority to operate in the EU under the U.S.-EU Open Skies agreement,” the airlines said.

The letter was referring to possible retaliation from the European Union and said restrictions “would also have a crippling impact on U.S. passenger carriers seeking new service to the EU.”

It was signed by the chief executive officers of the airlines.

“Undoubtedly, closing access to global markets will be a punishment that brings higher prices and fewer choices for American travelers, consumers, and shippers.”

JetBlue is also considering European destinations beyond London for future flights.

A group representing the three largest U.S. airlines, American Airlines Group Inc, Delta Air Lines Inc, United Continental Holdings Inc holds the opposite view and has said it is concerned about Qatar Airways is violating its agreement with the United States.

Qatar Airways has said its stake in Air Italy was “fully compliant” with the 2018 U.S.-Qatar Understandings, an additional pact that accompanied the U.S-Qatar Open Skies agreement.