The US administration has indicated that the government will closely examine a bid by Japan's largest steel maker to acquire US Steel. Washington says the company is a core part of American steel production, which in turn is critical to national security.

National Economic Advisor Lael Brainard issued a statement about the deal worth 14 billion dollar proposed by Nippon Steel.

The statement calls the American-owned company "iconic." It says President Joe Biden believes an attempt by a foreign entity to buy it deserves "serious scrutiny" regarding the impact on national security and supply chain reliability.

The economic advisor says the Biden administration has strengthened an inter-agency committee on foreign investment, and this is the kind of transaction it should carefully investigate.

The US administration says it will look at the results of the investigation and take action if necessary.

Nippon Steel announced on Monday that US Steel would become one of its subsidiaries between April and September next year, if approved by US Steel shareholders and authorities.

The announcement was met with opposition from the United Steelworkers union, as well as some US lawmakers.