North Korea has fired a ballistic missile in the first such test since Donald Trump took office as US president.
Mr. Trump assured Japan’s Prime Minister Shinzo Abe that “America stands behind Japan, its great ally, 100 per cent”.
The missile flew east towards the Sea of Japan for about 500km (300 miles), South Korean officials say.
Mr Abe said the test was “absolutely intolerable”. Japanese officials say the missile did not reach its waters.
Speaking at a joint conference during a visit to the US, Mr. Abe added that Mr. Trump had also assured him that he was committed to “further enforcing our alliance”.
During his election campaign, Mr. Trump said US defence commitments to Japan and South Korea were unfair and also called for Japan to pay the full cost of stationing US troops on its soil.
North Korea has conducted a number of nuclear and missile tests in the past year that continue to alarm and anger the region.
The tests are in contravention of UN resolutions designed to curb the North’s nuclear activities.
Sunday’s launch took place at 07:55 local time (22:55 GMT Saturday) from the Banghyon air base in North Pyongan province on the west side of the Korean peninsula.
The missile reached an altitude of about 550km (350 miles), the South Korean military said.
The military said it appeared to be a Musudan intermediate-range missile, capable of flying up to 4,000km and reaching the US territory of Guam in the Pacific Ocean.
In January, North Korean leader Kim Jong-un warned that his military was close to testing long-range missiles capable of reaching the United States mainland and carrying nuclear warheads.
Mr. Trump derided the claim in a tweet, saying: “It won’t happen.” BBC