US President Joe Biden is poised to officially block Nippon Steel’s proposed $14.9-billion purchase of US Steel, a person familiar with the matter said on Friday, dealing a probably fatal blow to the contentious merger plan.The Committee on Foreign Investment in the United States (CFIUS) spent months reviewing the deal for national security risks but referred the decision to Biden in December, after failing to reach a consensus.His decision could come as soon as Friday, despite the concerns of some of his senior advisers that it could hurt ties with key Asian ally Tokyo, according to the Washington Post, which first reported the news.The newspaper cited two administration officials who were not authorized to speak publicly about the matter.Shares of US Steel were down 7.8% in pre-market trade following the reports.Japan’s stock market was closed on Friday for a public holiday.Spokespersons for the White House and Nippon Steel declined comment.US Steel directed Reuters to its Thursday statement that it hoped “Biden will do the right thing and adhere to the law by approving a transaction that so clearly enhances US national and economic security.”Nippon paid a hefty premium to clinch the purchase of the No.2 US steel producer in a December 2023 auction, but the deal faced opposition from the powerful United Steelworkers union (USW), as well as politicians.Biden has previously said he wants US Steel to stay domestically owned and run, while President-elect Donald Trump has vowed to block a foreign takeover of the storied American firm after he takes office on January 20.In a November letter, Japanese Prime Minister Shigeru Ishiba urged Biden to approve the merger so as to avoid marring recent efforts to strengthen ties between the two countries, Reuters has exclusively reported.A spokesperson for Ishiba could not be reached for comment on Friday and Japan’s trade ministry declined to comment, saying there had been no formal ...