President Donald Trump says the United States will "take care of it" following North Korea's latest missile launch.
Trump told reporters that "it is a situation that we will handle."
The White House said earlier that Trump was briefed on North Korea's ballistic missile launch early Wednesday local time, its first in two months. Press secretary Sarah Sanders tweeted that Trump "was briefed, while missile was still in the air, on the situation in North Korea."
The Pentagon says it detected and tracked a single North Korean missile launch and believes it was an intercontinental ballistic missile.
He said the probable launch was detected at 1.30pm on Tuesday (0530 AEDT Wednesday).
NHK in Japan, citing the defence ministry, reported the missile flew for 50 minutes and landed in the water of Japan's exclusive economic zone.
Asahi Shimbun in Japan also reported that North Korea had fired a ballistic missile early on Wednesday.
North Korea fired the missile from Pyongsong, a city in South Pyongan Province, over the sea between South Korea and Japan, South Korea's Joint Chiefs of Staff said on Wednesday.
The missile flew to the east and the South Korean military is analysing details of the launch with the US in a bid to determine what type of missile was fired, the military said in a text.
Minutes after the North fired the missile, the South's military conducted a missile-firing test in response to the provocation, the South Korean military added.
After firing missiles at a rate of about two or three a month since April, North Korea paused its missile launches in late September, after it fired a missile that passed over Japan's northern Hokkaido island on September 15.
Last week, North Korea denounced Trump's decision to relist it as a state sponsor of terrorism, calling it a "serious provocation and violent infringement".
Trump has traded insults and threats with North Korean leader Kim Jong Un and warned in his maiden speech to the United Nations in September that the US would have no choice but to "totally destroy" North Korea if forced to defend itself or its allies.
Washington has said repeatedly that all options are on the table in dealing with North Korea, including military ones, but that it prefers a peaceful solution by Pyongyang agreeing to give up its nuclear and missile programs.
To this end, Trump has pursued a policy of encouraging countries around the world, including North Korea's main ally and neighbour, China, to step up sanctions on Pyongyang to persuade it to give up its weapons programs.