Japan’s novice foreign minister has a lot on his plate these days with nuclear-armed North Korea firing missiles over his country and US President Donald Trump threatening retaliation. But Taro Kono is now wrestling with his toughest diplomatic challenge yet: his dad. On Thursday, Kono, who took up the job just a month ago, was forced to fend off criticism from his retired politician father over Tokyo’s dealings with Pyongyang. Japanese media leapt on the story, with the right-wing Sankei newspaper carrying the headline “father-son dispute?” Yohei Kono – a former top government spokesman who made history in 1993 for his landmark apology over Japan’s use of sex slaves in the second world war – criticised his son’s foreign policy, saying there should be more cooperation with China to tackle North Korea’s sabre-rattling. China is the North’s chief ally and is seen as perhaps the only country that could convince the reclusive state to give up its nuclear weapons and missile programmes. “I’m not satisfied that enough is being done politically,” the 80-year-old said. “Japan, China and South Korea should unite and persuade North Korea ... The US isn’t the only country that can contain the North.” When asked about his son’s performance on the issue, the elder Kono paused, then said with a laugh: “Ummm ... It’s difficult to comment.” The younger Kono brushed off his old man’s slight, insisting Tokyo’s policy was sound. “Through foreign ministers’ meetings and telephone talks, we have shared with China and Russia a common recognition that the denuclearisation of the Korean peninsula is our goal,” he told reporters in New York.