President Donald Trump warned that the Supreme Court ruling against him in a key case on his power to apply tariffs would be the "biggest threat in history to United States National Security".

"We would be financially defenseless," Trump said in an early hours post on Truth Social, pointing to a report that the European Union is planning to apply new tariffs on China. "We would not be allowed to do what others already do!"

Trump said tariffs have "greatly enhanced" national security and that they had made the U.S. the "financially strongest" country in the world.

"Only dark and sinister forces would want to see that end!!!" Trump said.

This is a breaking news story. Updates to follow.

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