WASHINGTON, Sept 15 (Reuters) - The Trump administration

said late on Monday it is ordering Delta Air Lines ( DAL ) and

Aeromexico to unwind a joint venture by January 1 that lets them

coordinate on scheduling, pricing and capacity decisions for

U.S.-Mexico flights.

The U.S. Transportation Department in July had proposed the

action as part of a number of actions aimed at Mexican aviation.

The department said on Monday the action "is necessary because

of ongoing anticompetitive effects in U.S.-Mexico City markets

that provide an unfair advantage to Delta and Aeromexico."

The U.S. government is not requiring Delta to sell its 20%

equity stake in Aeromexico.