WASHINGTON (Reuters) -The Trump administration on Monday asked a U.S. appeals court to reject a bid by Delta Air Lines ( DAL ) and Aeromexico to halt an order forcing them to unwind a joint venture that lets the carriers coordinate scheduling, pricing and capacity for U.S.-Mexico flights.

The Transportation Department "validly decided to no longer authorize legalized collusion by two formerly competing airlines that control almost 60% of operations at the fourth-largest international gateway to and from the United States," the government said in a filing, citing Mexico City flights.