Trump said Japanese Prime Minister Shinzo Abe would be well-equipped for an attack from North Korea after buying equipment from the U.S.
"He will shoot them out of the sky when he completes the purchase of lots of additional military equipment from the United States," Trump told a press conference Monday.
"He will easily shoot them out of the sky, just like we shot something out of the sky the other day in Saudi Arabia, as you saw."
Trump was referring to a missile fired by Yemen, which was reportedly intercepted by Saudi Arabia over the weekend.
The president referred to that particular missile as "a needle in the sky," and said that the U.S. makes "the best military equipment by far."
He added that the purchasing of military equipment would bring both employment to the U.S. and safety to Japan.
"It's a lot of jobs for us, and a lot of safety for Japan, and other countries that are likewise purchasing military equipment from us, that frankly a year ago or two years ago were not."
Abe confirmed that Japan was planning to purchase military equipment from the U.S.
Abe added that the country would be prepared to shoot down a North Korean missile, if necessary, as part of its "legal cooperation" with the U.S.
"For the intercepting and shooting down, if it is necessary, of course we will do that," Abe said.
In August, a North Korean missile was flown over Japan. The rogue state has been hit with additional sanctions, in an effort to clamp down on its aggressive activities.
Trump is visiting Asia for a landmark tour from November 5 to 14, and will travel to South Korea, China, Vietnam and the Philippines next.