U.S. President Joe Biden has issued an order to halt Nippon Steel Corp.'s plan to acquire United States Steel Corp. This is an extraordinary case of intervention in a private business transaction.

Even though the investment comes from an allied nation, the U.S. is citing national security risks to block it. This can only be described as an unreasonable decision that undermines trust in the United States.

U.S. Steel, struggling with poor performance, ranks 24th in global steel production volume. It had agreed to a roughly $14.1-billion (approx. 2 trillion yen) acquisition proposal from Nippon Steel, which ranks fourth globally.

President Biden explained that placing a key industry under foreign control poses a national security risk. However, in the past, the U.S. government has only blocked acquisitions involving companies from politically adversarial nations like China.

The U.S. has so far worked with allied nations to build supply chains for semiconductors, which it considers critical materials, and has sought Japan's cooperation in imposing restrictions on exporting them to China. Overturning collaboration agreed upon by Japanese and American companies in the steel industry is inconsistent with this approach.

National security seems to be nothing more than a pretext, with the real aim being to appeal to domestic audiences by demonstrating a willingness to protect U.S. companies.

Once the world's largest steel producer, U.S. Steel has been regarded in the United States as a symbol of prosperity. There is strong resistance to foreign acquisitions, particularly from the United Steelworkers union. With some 1.2 million members, including retirees, the union wields significant influence.

Former Republican President Donald Trump, who won last year's presidential election, has openly opposed the acquisition. It is believed that President Biden, aiming to regain ground lost by the Democratic Party, has taken the union's stance into consideration.

However, protectionism that excludes foreign investment undermines national interests.

Nippon Steel has expressed its intention to expand its latest facilities in the U.S. to boost profits there. U.S. Steel has hinted that it may proceed with factory closures if the acquisition does not go through. This could also harm employment, which the union prioritizes.

If political motives take precedence over economic rationality, companies from Japan and other countries may hesitate to invest in America. The U.S. economy has thrived by championing free trade and actively welcoming foreign investment and talent.

There are concerns that this inward-looking stance, which began with the inauguration of the "America First" Trump administration in 2017, will gain further momentum. For the United States to turn its back on the open market would mean failing to fulfill the responsibilities of a great power in the international community.