KIEV, Aug. 7 – ArcelorMittal, the world’s biggest producer of steel, will “drastically” step up security at its Ukrainian plant and cooperate with law enforcement agencies as it seeks to prevent further attacks on its top managers.

Jean Robert Jouet, the chief executive officer at Arcelor Mittal Kryviy Rih, met Viktor Bondar, the governor of the Dnipropetrovsk region, and top law enforcement officials Thursday to plan the security measures.