West Coast cargo traffic was stalled Thursday by port workers staging day-long protests against the war in Iraq.

Thousands of members of the International Longshore and Warehouse Union did not show up to work in ports from Southern California to the Pacific Northwest, leaving ships and truck drivers idling.

The West Coast ports are the nation's gateway for cargo container traffic from Asia.

Union members previously had passed a resolution opposing the war and publicized plans for a co-ordinated protest through its website and newsletter.

The work stoppage defies Wednesday's order from an independent arbitrator to report to work as normal.

According to a release from the Pacific Maritime Association, responsible for negotiating agreements with the union, the ILWU president sent a recorded message to members Thursday saying, "I'm calling to let you know the entire longshore division will not work the day-side on Thursday."

At other ports, officials reportedly told members not to show up to work.

Steve Getzug, a spokesman with the PMA, said that shutting down the ports "in no way benefits an already-fragile U.S. economy."

“We are severely disappointed that the union leadership failed to keep its end of the bargain," Getzug said. "The Coast Arbitrator — essentially the Supreme Court on the waterfront — has ordered the union to treat today as a normal work day, but the union appears to have done the opposite.”

A spokesman for the National Retail Federation said shippers and exporters planned for the slowdown, which coincides with May Day, and expected no significant long-term disruptions.

With files from the Associated Press