The U.S. Department of Commerce has recommended that President Donald Trump consider imposing import curbs on steel and aluminum products, including those made in Japan.

The reason cited is that the increase in imports constitutes a national security threat, but imposing tariffs unilaterally for the interest of one’s own country runs counter to the principles of free trade.

Trump will make a decision on this recommendation by mid-April. If such curbs are imposed, this may distort the global trade order and trigger trade frictions between nations. He should refrain from taking this step.

Trump recently stated in a speech that the “America First” policy is not isolationist. If the U.S. introduces self-serving import restrictions, it will become even more isolated in the international community. It needs to seriously realize that this will have a negative impact not only on the U.S. economy, but also on its security and diplomacy.

The proposed import curbs will be based on Section 232 of the Trade Expansion Act. While the main target is said to be China, which is overproducing steel, the recommendation also calls for imposing tariff duties and import quotas on all countries. This is probably due to the suspicion that China is exporting to the U.S. via third countries.

The World Trade Organization (WTO) prohibits the unilateral imposition of restrictions on imports from other countries, with exceptions only for security reasons. The U.S.’s reasoning is that domestic industries supporting the military are being weakened by the influx of imports, thus undermining national security.

This argument can hardly hold water. In the first place, how real is the threat that the U.S. is talking about? The fact that Japan and other U.S. allies will also be targeted shows that the security reason is far from convincing.

Trump probably wants to demonstrate his aggressive trade diplomacy with the mid-term elections this fall in mind. Yet an increase in the prices of steel and aluminum products resulting from import curbs will deal a blow to the manufacturing industries using these products. The administration should give serious thought to the industrial sector’s opposition to import restrictions.

The U.S.’s resentment of China’s unfair trade practices is understandable. The solution to this should be the reinforcement of the international encirclement of China. It is obvious who will benefit from the U.S.’s abandoning its role in this reinforcement and becoming a global target of criticism over protectionism.

Minister of Economy, Trade and Industry Hiroshige Seko was correct in saying “imports from Japan do not affect U.S. national security.” However, this is not a problem only for Japan. In order to stop a chain reaction of protectionism, Japan needs to cooperate with Europe in making greater efforts to persuade the U.S. not to go in the direction of isolation.