Iron ore and coal miner Cliffs Natural Resources has become the third major U.S. company in the past six months to seek creditor protection for its Canadian arm to try to isolate losses and protect shareholders, Reuters reported yesterday. The mining company said that it had commenced restructuring proceedings yesterday in Montreal. The move mirrors the route taken by U.S. Steel, which sought creditor protection for its money-losing Canadian operations in September, and by U.S. discount retailer Target Corp., which announced this month it was abandoning its Canadian expansion. The long-anticipated move by Cliffs will help insulate the publicly listed U.S. parent company from the vast majority of the $650 million to $700 million in closure costs tied to its mothballed assets in Canada.