Washington, April 3 (IANS): US presidential candidate and Republican front-runner Donald Trump reiterated his belief that Japan should arm itself to deter a threat from North Korea rather than have the US military protect the longtime ally against the rogue nuclear nation.

"I would rather have them not arm, but I'm not going to continue to lose this tremendous amount of money. And frankly, the case could be made that let them protect themselves against North Korea. They'd probably wipe them out pretty quick," Trump said at a campaign event in Wasau, Wisconsin on Saturday.

Trump added, "If they fight, you know what, that'd be a terrible thing. Terrible. ... But if they do, they do," CNN reported.

Earlier this week, Trump startled Japan and South Korea, two of US' strongest allies, with the suggestion that the US military should be withdrawn from their shores, with nuclear weapons replacing them.

There are currently 54,000 US troops stationed in Japan and 28,500 in South Korea.

"We can't be the policeman to the world and have $19 trillion in debt, going up to $21 trillion," he said.

Trump, who appeared at three campaign events throughout Wisconsin on Saturday, reiterated his claim that many of the nations in NATO are "not paying their fair share".

"Either they pay up, including for past deficiencies, or they have to get out. And if it breaks up NATO, it breaks up NATO," Trump said at a rally in Racine, Wisconsin.

The presidential front-runner also questioned the Washington's relationship with Saudi Arabia where he accused the oil-rich nation of not pitching in a "fair pay" for US defence.