A massive strike across the U.S. East and Gulf Coast ports has been averted after a dockworker union and an alliance of companies, terminal operators, and port associations negotiated a new labor contract.

A tentative agreement between a dockworkers union and a shippers association was announced Wednesday night, averting a Jan. 15 strike deadline that experts said might have been tough to endure. No details about how the proposed pact were announced between the International Longshoremen’s Association union and the United States Maritime Alliance,

The union representing 45,000 dock workers on the U.S. East and Gulf Coasts and their employers on Wednesday said they reached a tentative deal on a new six-year contract, averting further strikes that could have snarled supply chains and taken a toll on the U.