A union filed strike notice against Canada’s largest railway on Aug. 23 just hours after trains began rolling again, likely derailing plans to revive vital shipping networks.

Canada’s two largest railways are preparing to restart operations after the country's government stepped in to try to end a labor dispute that has halted freight movement.

TORONTO — CN is ending its lockout immediately and moving forward with a plan to get its trains moving again following an order to enter forced arbitration with its union, a rail official says.

Two mining giants are rerouting shipments and turning to trucks to deal with disruptions from a Canadian railway stoppage that threatens to undermine the industry’s operations.

Importers and exporters are left with few options as a near-total rail shutdown in Canada risks delaying ocean shipments, spiking freight costs and straining the busiest U.S. ports.

The Canadian railway system has been struck with two major work stoppages amid failed labor negotiations Aug. 22.

Prime Minister Justin Trudeau is urging Canada’s two largest railways and unionized workers to reach a deal to avert a strike that businesses warn will cause significant harm to the economy.

Canadian businesses are warning about potential long-term damage to the economy if railway and port strikes go ahead and choke the country’s vital trading arteries.

The Canadian government has denied an arbitration request by Canadian National Railway Co., increasing the likelihood of a nationwide work stoppage by thousands of its unionized workers.

The ruling found that a work stoppage between the Teamsters and rail companies would not pose an immediate threat to public health and safety, meaning a strike could occur as soon as Aug. 22.