Speaking in the Philippines, in the company of his US and South Korean counterparts, Itsunori Onodera said it was essential those countries concerned about the threat acted to confront it.
“[The] threat posed by North Korea has grown to the unprecedented, critical and imminent level,” he said.
According to Reuters, he added: “Therefore, we have to take calibrated and different responses to meet with that level of threat.”
The comments from Mr Onodera came amid escalating tension between North Korea and the West. Since Kim Jong-un assumed leadership of the country in 2011, he has overseen a rapid escalation of its nuclear weapons programme.
In recent months, it has continued to test intercontinental ballistic missiles, despite repeated calls from the international community not to do so. Many experts believe those missiles - which North Korea has tested by firing them over Japan - could reach the US mainland. At the same time, it has also been testing the nuclear payloads that could be carried by such missiles.
The US has responded by sabre-rattling and a barrage of rhetoric. During his first speech before the United Nations General Assembly, Donald Trump said the US may be obliged to “totally destroy” North Korea. He has also denounced the outreach endeavours of his top diplomat, Secretary of State, Rex Tillerson.
“I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man,” Mr Trump said on Twitter earlier this month, using the nickname he has adopted for the North Korean leader. “Save your energy Rex. We’ll do what has to be done!”
Mr Onodera’s remarks, which highlighted the deep concern in Tokyo about North Korea’s weapons testing, were more outspoken than the comments from US Defence Secretary Jim Mattis and South Korean Defense Minister Song Young-Moo.
Mr Song said “North Korea’s provocative behaviour is becoming worse and worse”. Mr Mattis also renewed criticism of North Korea’s tests, saying they “threaten regional and global security”.
Meanwhile, former US President Jimmy Carter said he was willing to travel to North Korea on behalf of the Trump administration to try and help diffuse the situation, the New York Times reported over the weekend.
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