() President Donald Trump’s threat to use tariffs against other countries is causing confusion and uncertainty in the market that will come back and haunt the United States, according to the president’s former national security adviser.

John Bolton, who served in the role during Trump’s first presidency, told that the threat of tariffs directed at countries like Canada and Mexico is the wrong approach to reaching his goal for economic supremacy.

“China is the problem,” Bolton told . “China is dumping steel and aluminum, and so if that’s the problem and they’re not playing by pretrade rules, which is clearly the case, then I think the United States is entirely justified in retaliating.”

But rather than getting countries that have been harmed by China together to fight back, Trump has, Bolton said, chosen to “slap Canada in the face” with threats of tariffs. He said rather than addressing the enemy, Bolton said the president has directed his anger in the wrong direction.

Trump’s bigger agenda could be potentially “very damaging” to the American economy, Bolton said.

China imposed duties on U.S. imports on Monday, just hours after Trump announced he wanted to place 25% tariffs on all steel and aluminum coming into the country. Even before being elected, Trump was not shy about his love of tariffs, calling them “the greatest thing invented.”

The president will eventually need to put his plan in writing, Bolton said, rather than “making numbers up to bargain (with) and scare people.”

Trump has announced that he plans to generate lost revenue through tariffs, which Bolton said will ultimately result in higher taxes for Americans. An analysis by the nonpartisan Peterson Institute for International Economics estimates Trump’s proposed tariffs would cost a typical U.S. household more than $2,600 a year.

“I think it’s economic self-harm to the United States,” Bolton said.