White House trade advisor Peter Navarro speaks to members of the media near the West Wing of the White House in Washington, D.C., U.S., August 21, 2025.

President Donald Trump’s trade adviser Peter Navarro said Sunday that “it will be the end of the United States” if the president’s sweeping tariffs are ultimately blocked by the U.S. Supreme Court.

Navarro’s comments echoed Trump’s own rhetoric as the president sharply criticized last week’s 7-4 appeals court decision, which ruled that most of Trump’s tariffs are illegal, placing a central tenet of the administration’s economic agenda on shaky ground.

The final ruling on the matter is likely to be decided by the U.S. Supreme Court. As the battle over Trump’s tariffs intensifies, the president’s advisers are casting the ultimate outcome as pivotal to the future of the country.

“This was weaponized partisan injustice at its worst,” Navarro said on Fox’s “Sunday Morning Futures.”

“If we lose the case, President Trump is right. It will be the end of the United States,” he said.

Navarro also said that he feels “very optimistic” about the administration’s arguments to the Supreme Court.

“A very good dissent provides a road map for the Supreme Court. We feel very optimistic,” Navarro said.

The White House did not immediately respond to CNBC’s request to comment.