Some aspects of operations at the Ports of Los Angeles, Long Beach, Oakland and Seattle closed or slowed last week following protracted labor negotiations, hinting at past disputes that led to interruptions in national supply chains.

The disruptions come as the International Longshore and Warehouse Union and Pacific Maritime Association, which represents shipping terminal operators, have been in discussions for over a year without reaching a new labor agreement.

The two parties have agreed on sticky issues relating to automation and benefits but are stuck on pay, The Washington Post reported, citing two people with knowledge of the negotiations. The ILWU represents more than 22,000 workers at 29 West Coast ports.

The disruptions reported included a closure at the Port of Oakland on Friday, though the port was open in all of its terminals again on Monday. At the Port of Los Angeles on Friday and Monday, some terminals canceled pickup appointments for truckers retrieving imports, the Post reported. Labor shortages were reportedly the cause of the disruptions in both cases.

PMA in a Friday statement posted to its Twitter account framed the instances as the ILWU engaging in "concerted and disruptive work actions" that slowed operations. The organization said actions like these contribute to retailers and manufacturers diverting their cargo to ports on the East and Gulf coasts.

"West Coast dockworkers kept the economy going during the pandemic and lost their lives doing so," ILWU President Willie Adams said in a statement posted Friday to the organization's Twitter account. "We aren’t going to settle for an economic package that doesn’t recognize the heroic efforts and personal sacrifices of the ILWU workforce that lifted the shipping industry to record profits.”

Retailers have taken notice of not only the activities at the port but also the lengthy negotiations and have asked for President Joe Biden to intervene.

"As we enter the peak shipping season for the holidays, these additional disruptions will force retailers and other important shipping partners to continue to shift cargo away from the West Coast ports until a new labor contract is established," the National Retail Federation said in a statement. "It is imperative that the parties return to the negotiating table. We urge the administration to mediate to ensure the parties quickly finalize a new contract without additional disruptions.”