WASHINGTON (Reuters) -Delta Air Lines ( DAL ) and Aeromexico challenged a Trump administration decision ordering them to unwind a joint venture by January 1 that let the carriers coordinate scheduling, pricing and capacity decisions for U.S.-Mexico flights.

The companies filed a legal challenge to the U.S. Transportation Department decision last month in the 11th Circuit Court of Appeals that was made public Friday. The department ordered an end to the nearly nine-year-old joint venture as part of a number of actions aimed at Mexican aviation, citing competition concerns.