U.S. Trade Representative Greer Says U.S. Needs To Resolve Dairy Issues With Canada Through USMCA Negotiations Or Through An Enforcement Action; If Mexico, Canada Want Preferential Trade Access To U.S., They Need To Control Their Economic Borders, Including On Subsidized Autos From China; Willing To Look At Using Trade Tools To Protect U.S. Sugar Producers; Canadian Counterparts Have Made No Commitments To Alter Dairy Trade Thus Far