US President Joe Biden has prohibited the proposed acquisition of US Steel by Japan’s Nippon Steel.

Biden found that through the acquisition, Nippon might take action that threatens to impair the national security of the United States, the White House says in a statement seen by Kallanish.

Moreover, “Provisions of law, other than section 721 and the International Emergency Economic Powers Act (50 U.S.C. 1701 et seq.), do not, in my judgment, provide adequate and appropriate authority for me to protect the national security in this matter,” Biden comments.

Nippon and US Steel must now permanently abandon the proposed deal within 30 days, unless this deadline is extended by the Committee on Foreign Investment in the United States (CFIUS).

Until then, the firms must certify to CFIUS on a weekly basis that they are “in compliance with this order and include with that certification a description of all efforts to fully and permanently abandon the Proposed Transaction,” the note reads.

“Any transaction or other instrument entered into or method employed for the purpose of, or with the effect of, evading or circumventing this order is prohibited,” it adds.

The president’s order brings to an end a year-long saga which saw the proposed circa $15 billion acquisition face strong political opposition in the US ever since it was first announced in December 2023. Both Biden and US President-elect Donald Trump had vowed to block the deal, putting into question the relationship between allies US and Japan.

The decision was ultimately referred to Biden last month after the CFIUS could not reach a consensus about whether the deal poses a national security threat, following a long investigation. In a last-ditch attempt to secure the deal this week, Nippon Steel offered the US government a veto on any cuts to production in the next ten years if it were to acquire US Steel.