WASHINGTON (Reuters) -A U.S. appeals court late on Wednesday temporarily halted a Trump administration order to force Delta Air Lines ( DAL ) and Aeromexico to unwind a joint venture by January 1.

The airlines had sued to block the Transportation Department order to reverse the nearly nine-year-old joint venture that lets the carriers coordinate scheduling, pricing and capacity for U.S.-Mexico flights.

The carriers said they faced substantial costs they could not recover even if a court later upheld the arrangement.