North Korea has fired another ballistic missile which is believed to have landed in the water of Japan's exclusive economic zone.
The missile launch has been reported by the South Korean news agency Yonhap, citing authorities in the country's military.
Yonhap said the unidentified ballistic missile was fired from South Pyongan Province and flew eastward.
NHK in Japan, citing the defence ministry, reported that the missile may have landed in the water of Japan's exclusive economic zone.
Two missiles fired by North Korea earlier this year flew over Japan.
South Korea and Japan had recently detected signs of a possible missile launch and have been on higher alert.
North Korea is pursuing its nuclear weapons and missile programmes 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.
The launch came a week after President Donald Trump put North Korea back on a US list of countries that it says support terrorism.
Later, the Pentagon said that it had detected a "probable" missile launch from North Korea.
"We detected a probable missile launch from North Korea. We are in the process of assessing the situation and will provide additional details when available," Pentagon spokesman Colonel Robert Manning told reporters.
He said the probable launch was detected at 1.30 pm EST (7.30am NZT).
US stocks pared gains after reports of the missile launch. The S&P 500 index was up half a percent in mid-afternoon.
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 15 September.
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."
The designation allows the United States to impose more sanctions, though some experts said it risked inflaming tensions.
Mr 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 United States 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, Mr 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.
North Korea has given no indication it is willing to re-enter dialogue on those terms.
North Korea defends its weapons programs as a necessary defence against U.S. plans to invade. The United States, which has 28,500 troops in South Korea as a legacy of the 1950-53 Korean War, denies any such intention.