Talks were resumed but have halted again after nearly reaching an agreement on Friday, said sources familiar with the negotiations. After the latest breakdown between the two sides, Steelworkers leaders targeted Shell, which is the U.S. arm of Royal Dutch Shell Plc, calling workers out at a chemical plant and three refineries in the company's Motiva Enterprises [MOTIV.UL] joint-venture with Saudi Aramco [SDABO.UL]. The first work stoppage of the three refineries was at the nation's largest, the 600,250 barrel per day Port Arthur, Texas, refinery, where workers walked out at 12 a.m. on Saturday. Twenty-four hours later, USW members were also picketing at Motiva's 235,000 bpd Convent, Louisiana, and 238,000 bpd Norco, Louisiana, refineries and the Shell chemical plant in Norco. In announcing the strikes, USW International union President Leo Gerard said they were the result of the industry's bargaining tactics.