HARRISBURG, Pa. (AP) — Nippon Steel and U.S. Steel say they’ve finalized their “historic partnership,” a year-and-a-half after the Japanese company first proposed its deal to buy the iconic American steelmaker for nearly $15 billion. The bid by Nippon Steel was buffeted by national security concerns and presidential politics, delaying the transaction for more than a year after U.S. Steel shareholders approved it. It also forced Nippon Steel to expand the deal, including giving the federal government a say in some matters. The combined company will become the world’s fourth-largest steelmaker, and bring what analysts say is Nippon Steel’s top-notch technology to U.S. Steel. In exchange, Nippon Steel gets access to a robust U.S. steel market.