Donald Trump has reportedly questioned why “samurai” Japan did not shoot down North Korean missiles earlier this year.

In advance of his trip to Japan this week, Mr Trump is said to have told leaders from Southeast Asian countries on the phone that he couldn't understand why “a country of samurai warriors” didn't take military action against provocations from North Korea, according to the Japan Times.

North Korea has fired two nuclear missiles over Japan this year, on 29 August and 15 September. Both flew over Hokkaido before falling into the Pacific Ocean.

Japan’s Self-Defense Forces did not try to stop the missiles, with the government saying that the SDF had monitored the rockets from launch and determined they would not land on Japanese territory, the Japan Times reported.

Japan’s policy is that it would only shoot down a missile if it were falling on Japanese territory or if it were judged to pose an “existential threat” to Japan because it was aimed at a US target.

The altitude and speed of the missiles would have made it very difficult to destroy them in flight, the Japan Times said.

But Mr Trump, who has repeatedly taken an aggressive tone in his comments about North Korea, seems to have wished Japan had acted differently.

On Monday, speaking after a summit with Japanese Prime Minister Shinzo Abe, Mr Trump said Japan would shoot North Korean missiles “out of the sky” if it bought the US weaponry needed for doing so.

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He repeated his mantra that the “era of strategic patience” with North Korea was over, adding that Japan and the US were working to counter the “dangerous aggressions”.

North Korea is pursuing a ballistic and nuclear weapons programme in defiance of UN Security Council sanctions and has made no secret of its plans to develop a missile capable of hitting the US mainland.

“He (Abe) will shoot them out of the sky when he completes the purchase of lots of additional military equipment from the United States,” Mr Trump said, referring to the North Korean missiles. “The prime minister is going to be purchasing massive amounts of military equipment, as he should. And we make the best military equipment by far.”

Mr Trump was replying to a question that was posed to Mr Abe. A reporter asked Mr Abe for a response to Mr Trump’s comments saying that Japan was a “samurai” nation and should have shot down the North Korean missiles, according to Reuters.