Air Canada said Sunday it was suspending its plans to return to work until Monday. The airline’s decision follows a decision by the Canadian Union of Public Employees, which represents about 10,000 flight attendants, to defy an order by the Canadian Industrial Relations Board to return to work.

After months of stalled negotiations, 10,000 Air Canada flight attendants walked off the job early Saturday morning. The federal government stepped in hours later to order binding arbitration, forcing an end to the strike — or so they thought.