White House trade adviser Peter Navarro apologized for suggesting Canadian Prime Minister Justin Trudeau deserved a “special place in hell” for a perceived breach in protocol against U.S. President Donald Trump.

“My job was to send a signal of strength,” he said at a conference in Washington on Tuesday. “The problem was that in conveying that message I used language that was inappropriate.”

“I own that, that was my mistake, those were my words.”

Navarro, a supporter of tariffs to help reduce the U.S.’s trade deficit and a longtime critic of China, turned his anger at Canada over the weekend as a Group of Seven meeting hosted by Trudeau ended in disarray and trade war threats.

“There’s a special place in hell for any foreign leader that engages in bad faith diplomacy with President Donald J. Trump and then tries to stab him in the back on the way out the door,” Navarro said on “Fox News Sunday.”

At his closing press conference, Trudeau called U.S. steel and aluminum tariffs “insulting” and pledged to proceed with previously announced retaliatory tariffs.