Nuclear-armed North Korea fired a ballistic missile into the Sea of Japan on Wednesday, in what analysts said was a warning ahead of a China-US summit at which Pyongyang's accelerating atomic weapons programme is set to top the agenda.
South Korea's defence ministry said the missile -? launched days after Pyongyang warned of retaliation if the global community ramps up sanctions -- had flown 60 kilometres (about 40 miles).
The incident represented a "threat to the peace and stability of the whole world", Seoul said, while Japanese Prime Minister Shinzo Abe labelled it a "grave provocation".
In a terse statement, US Secretary of State Rex Tillerson said: "The United States has spoken enough about North Korea. We have no further comment."
The launch -- a KN-15 medium-range ballistic missile -- will fuel international concerns about the hermit state's weapons programme.
Pyongyang is on a quest to develop a long-range missile capable of hitting the US mainland with a nuclear warhead, and has so far staged five nuclear tests, two of them last year.
- Trump-Xi meeting -
The latest launch came after President Donald Trump threatened the US was prepared to go it alone in bringing the North to heel.
His comments, in an interview with the Financial Times, were interpreted as an effort to up the pressure on Beijing ahead of a summit on Thursday and Friday.
Trump will host China's President Xi Jinping at his Mar-a-Lago resort in Florida for their first face-to-face meeting, where the growing tensions on the Korean peninsula are expected to be high on the agenda.
The Trump administration has repeatedly insisted that Beijing holds the key to stopping its errant neighbour and is not doing enough to control it.
China is North Korea's sole major diplomatic friend and a key trading partner that supplies the isolated state with much of its hard currency in the face of stringent global sanctions.
But Beijing is wary of putting too much pressure on North Korea for fear of the unpredictable consequences if the regime collapses.
Chang Yong-Seok, a researcher at the Seoul National University's Institute for Peace and Unification Studies, said the missile test was Pyongyang's way of warning China and the US.
It was "a show of force to demonstrate its might against potential extra deployment of US troops and weapons near the peninsula".
"There is a possibility that the North may take it up a notch and stage another nuclear test ... depending on the outcome of the summit."
- 'Reckless' -
North Korea's foreign ministry on Monday assailed Washington for its tough talk and for an ongoing joint military exercise with South Korea and Japan which Pyongyang sees as a dress rehearsal for invasion.
The "reckless actions" are driving the tense situation on the Korean peninsula "to the brink of a war", a ministry spokesman was quoted as saying by the official KCNA news agency.
The idea that the US could deprive Pyongyang of its "nuclear deterrent" through sanctions is "the wildest dream", it said.
The hardened US stance followed recent North Korean missile launches that Pyongyang described as practice for an attack on US bases in Japan.
In February the North simultaneously fired four ballistic missiles off its east coast, three of which fell provocatively close to Japan.
Last August Pyongyang also successfully test-fired a submarine-launched ballistic missile 500 kilometres towards Japan, far exceeding any previous sub-launched tests, in what the North's leader Kim Jong-Un hailed as the "greatest success".
A nuclear-capable SLBM system would take the North's threat to a new level, allowing deployment far beyond the Korean peninsula and a "second-strike" capability in the event of an attack on its army bases.
Analysts say that while Pyongyang has made faster progress in its SLBM system than originally expected, it is still years away from deployment.
Pyongyang is barred under UN resolutions from carrying out ballistic missile launches or nuclear tests.