US President Donald Trump has said Japan could shoot North Korean missiles “out of the sky” with military equipment bought from the US.
Japan’s PM Shinzo Abe meanwhile said his country could intercept missiles “if necessary”.
The two leaders were speaking to reporters at the close of Mr Trump’s first state visit to Japan.
North Korea has fired long-range ballistic missiles over Japanese territory twice in recent months.
On Monday, while answering questions at a press conference, Mr Trump said Mr Abe was “going to purchase massive amounts of military equipment” from the US.
Referencing North Korea’s missiles, he said Mr Abe could “shoot them out of the sky” when he completed the purchase, which he said would provide jobs to Americans as well as “safety for Japan”.
Mr Abe said Japan had to “qualitatively and quantitatively” enhance its defence capability, given the “very tough” North Korea situation.
He stressed that missile defence was based on “legal co-operation” between Japan and the US, and as for shooting down missiles, “if necessary of course we can do that”.
It is not clear whether a military deal has been signed during Mr Trump’s trip, but the two countries are close military allies with the US maintaining several military bases in Japan.
In September Mr Trump had tweeted that he would allow the sale of high-end military equipment to Japan and South Korea.
Japan does not have a standing army, but instead maintains what it calls a self-defence force, under its post-war pacifist constitution which the hawkish Mr Abe has been seeking to revise.
The two leaders also reaffirmed their ties and pledged to “stand against the North Korean menace”, said Mr Trump.
Mr Trump is visiting Japan as part of his first tour of Asia as US president.
Earlier in his visit he also visited a US air base near Tokyo, and met American business leaders where he publically criticised Japan over a trade deficit.
Mr Trump will be visiting South Korea, China, Vietnam and the Philippines in the coming week.