Deputy Prime Minister Taro Aso has raised the specter of armed North Korean refugees flooding the Sea of Japan coastline after a contingency on the Korean Peninsula, and asked whether they would be shot as part of Japan's response.

In a speech in Utsunomiya, Tochigi Prefecture, on Saturday, Aso, who is also the finance minister, asked how authorities would respond if that should happen.

"Can the police handle them? Will the Self-Defense Forces be dispatched and shoot them down? We'd better think about it seriously," he claimed.

The United States and North Korea remain on high alert as their leaders continue to hurl nuclear threats at each other.

In the event of a Korean "contingency," there is speculation that a large number of refugees from the impoverished, starving nation could make their way to Japan.

Citing an estimate of over 100,000 appearing along Sea of Japan coast prefectures like Niigata, Yamagata and Aomori, with some possibly armed, Aso asked: "Will police respond and arrest them on charges of illegal immigration? If the SDF are dispatched, will they shoot them down?"

Aso also suggested that the government should also discuss where such refugees would be held.

"It's a politician's job to think of (an emergency) response. It may not be an event in the distant future," he said.