President Joe Biden said Friday he is blocking a $14.3 billion acquisition of US Steel by Japan’s Nippon Steel, marking a significant use of executive authority in the closing days of his administration.

President Joe Biden has rejected the nearly $15 billion proposed deal for Nippon Steel of Japan to purchase Pittsburgh-based U.S. Steel.

The president said he was moving to protect national security in deciding the fate of the iconic Pennsylvania-based company, which became a contentious political issue in an election year.