The Supreme Court of the United States. AFP Yonhap News

President Donald Trump reiterated on the 9th (local time) that the U.S. security and economy would suffer significant damage if the Supreme Court ruled that the administration's tariff policy was illegal.

In a post on the social media platform Truth Social on the same day, President Trump stated, "A negative ruling by the Supreme Court on tariffs would be the greatest threat in history to U.S. national security," adding, "We would be financially defenseless."

He mentioned that Europe imposes tariffs on China and other countries, and added, "We would be unable to do what other countries are already doing (imposing tariffs)."

He further asserted, "Thanks to tariffs, which can be applied easily and quickly, our national security has greatly improved, and we have become the financially strongest nation anywhere in the world. Only dark and evil forces would want to see it end."

The Supreme Court is currently reviewing the legality of various tariffs imposed by President Trump on countries worldwide under the International Emergency Economic Powers Act (IEEPA), and a ruling could come as early as this year.

The IEEPA, enacted in 1977, grants the President the authority to regulate imports. President Trump has used this law to quickly impose tariffs through his executive orders, bypassing Congress which holds the power to tax.

However, lower courts have ruled that the import regulation authority granted to the President by the IEEPA does not include the authority to impose tariffs through executive orders.

Since then, President Trump and administration officials have argued that if the Supreme Court rules IEEPA tariffs illegal, they may have to refund tariffs already collected, and that trade agreements with other countries, which rely on tariffs as leverage, could become void, causing significant damage to the U.S. economy.