Panama’s president rebuffed Donald Trump’s threat to reimpose US control over the Panama Canal, saying its shipping tolls aren’t inflated and that sovereignty over the waterway isn’t negotiable.

U.S. president-elect Donald Trump threatened on Sunday to reassert U.S. control over the Panama Canal, accusing Panama of charging excessive rates to use the Central American passage. The comments drew a sharp rebuke from Panamanian President José Raúl Mulino.

President-elect Donald Trump is decrying the increased fees Panama has imposed to use the waterway linking the Atlantic and Pacific oceans.