The Pacific Maritime Association is accusing the International Longshore and Warehouse Union of orchestrating a deliberate slowdown of container movement at the ports of Los Angeles and Long Beach, after initiating similar actions earlier this week at the ports of Seattle and Tacoma.

The association said the union is refusing to dispatch hundreds of skilled workers for critically important positions transporting containers in terminal yards, breaking an agreement the two had groups reached to continue normal operations.

“This is a bold-faced lie,” the ILWU said in a statement. “No such agreement was ever made, nor could it be made given the parties’ historic disagreement regarding the definition of ‘normal operations’ – a disagreement that has been the subject of arbitrations for decades.” The Union said that the association, which represents shipping companies in labor negotiations, is attempting to deflect blame for congestion.

Terminal congestion has been a mounting issue at the ports of Long Beach and Los Angeles, which collectively handle 70 percent of West Coast cargo. The holdups come at the tail end of peak shipping season, when retailers import holiday items. The association said the congestion has been caused by a surge in cargo volume, a shortage of truck trailers and rail cars, and a shortage of truck drivers.

Negotiations for a new coast-wide contract covering nearly 13,600 registered workers began in May between the association and the longshore workers. When the old labor contract covering dockworkers expired in July, the two sides issued a joint statement saying normal operations would continue until a deal was done, the PMA claims.