The union representing 10,000 striking Air Canada flight attendants said Sunday it will challenge an order for them to return to work, adding that “we remain on strike.”

Air Canada said it plans to resume flights on Sunday after the Canadian government intervened and forced the airline and its striking flight attendants back to work and into arbitration.

“The impact of the work stoppage at Air Canada that began early this morning is already being felt by travelers,” Patty Hajdu, the labor minister in the Liberal government, told reporters.