A possible strike by the International Longshoremen’s Association  could bring Port of Houston container shipment traffic to a standstill shortly after Christmas.

ILA head Harold Daggett sent a letter to ILA unions across the nation telling them to get ready for a “coastwide strike beginning at 12:01 a.m. Sunday, Dec. 30.” Contract negotiations had been ongoing between the group and the U.S. Maritime Alliance, which represents container carriers and maritime terminals on the U.S. East and Gulf coasts, but negotiations stalled.

Maritime attorneys, who often represent longshoremen in injury cases, know how vital these workers are to the U.S. economy. The ILA represents 14,500 workers at 15 ports in the United States, including the Port of Houston. They are essential to the loading and offloading of goods from ships.

A key sticking point in the talks has been container royalties, which ILA union workers receive based on the weight of cargo received at each port. The National Retail Federation and the National Association of Manufacturers, among other groups, have urged the federal government to step in to reopen negotiations.