Former U.S. National Security Adviser John Bolton says the Donald Trump administration is not getting as tough as it can and should on North Korea. 

According to Axios on Sunday, Bolton, who was known for his hawkish positions toward the North before he lost the job in September, sharpened his criticism of his former boss in an interview with the U.S.-based online media outlet last week. 

Bolton said that Trump’s argument that he has stopped Pyongyang’s nuclear ambitions is a bluff and that the president soon might need to admit publicly that his North Korea policy “failed badly.” 

He said Washington will be pursuing “a different course” if it really means to dissuade the North from possessing deliverable nuclear weapons, pointing to what he called lack of action by the U.S. Navy in intercepting illegal oil transfers at sea bound for the North. 

Bolton called on the U.S. government to ditch a “rhetorical policy” and demonstrate to the North that it will not accept its nuclear armament.