The decision by the United Auto Workers on Saturday to call a fresh strike at General Motors as talks appeared to be nearing a conclusion was the latest in a set of unexpected moves by the union, which has used misdirection and maximized publicity to keep companies off balance.

The surprise walkout at a factory in Tennessee followed several days of intensifying contract negotiations between GM and union leaders, including meetings involving GM Chief Executive Mary Barra and UAW President Shawn Fain. The escalation of the strike came as the UAW confirmed that it reached a tentative agreement with Chrysler-parent Stellantis on a new labor contract.