Japan might have only minutes to prepare for nuclear attacks, said officials in the island nation as they face down threats from demented North Korean dictator Kim Jong Un.

Tokyo is asking for all its regional governments to sharpen alert plans should Pyongyang’s tubby tyrant press the button and send nukes flying over the Sea of Japan.

Officials in Tokyo — Japan’s largest city with 13.5 million citizens — said their residents might have as little as 10 minutes to act.

And even more concerning, Osaka Mayor Hirofumi Yoshimura said the 2.6 million residents of Japan’s third-largest city might have as little as four minutes to run for their lives and take shelter.

“A missile may not be detected as soon as it leaves the launch pad … and that could take several minutes,” Yoshimura told the Japan Times.

“The warning and alarms might only sound four or five minutes before a missile arrives.”

As North Korea continues to make nuclear threats, Japanese citizens are becoming increasingly fearful that they — and not Pyongyang’s sworn enemies in Seoul and Washington, DC — could be Kim’s first targets.

Japan’s civil defense website received 5.7 million visitors in the first 23 days of this month — a massive hike from its usual monthly traffic of less than 400,000 hits, the Washington Post reported.

The prime minister’s office issued new “actions to protect yourself” guidelines this week — which pretty much amount to taking cover inside well-constructed buildings.

Under the site’s FAQs, Japanese officials said citizens will have only minutes to act.

“When a missile is launched from North Korea, it will not take long to reach Japan,” it answered. “For example, the ballistic missile launched from (North Korea) on February 7 last year took 10 minutes to fly over Okinawa.”

US Vice President Mike Pence last week reaffirmed the Trump administration’s alliance with Japan amid the recent provocations from the hermit kingdom.