North Korea fired a ballistic missile yesterday, its first provocation since Donald Trump was elected President of the United States and one that sets up a test for the new Administration in Washington.
The launch happened while Trump was hosting Japanese Prime Minister Shinzo Abe at his Mar-A-Lago golf resort in Florida.
Abe said: "North Korea's most recent missile launch is absolutely intolerable," during a joint press conference.
"I just want everybody to understand and fully know that the United States of America stands behind Japan, it's great ally, 100 per cent," Trump said.
Trump, who dined with Abe at his Florida home, earlier declined to respond to reporters' questions about the missile test.
In a ballroom at Trump's south Florida estate, Abe read a brief statement in which he called on the North to comply fully with relevant UN Security Council resolutions. He said Trump has assured him of US support and that Trump's presence showed the president's determination and commitment.
South Korea's presidential Blue House said the presidential security director Kim Kwan Jin spoke to Trump's national security adviser Michael Flynn over the phone following test launch.
The missile was fired shortly before 8am local time from a known test site in North Pyongan province in the west of the country, not far from the border with China, and flew over the Korean Peninsula and into the Sea of Japan, South Korea's joint chiefs of staff said.
They were still working to analyse data from the projectile but said it appeared to be a medium-range Musudan missile, the type that North Korea had been trying to perfect last year.
The Musudan is technically capable of flying as far as 3860km, putting Guam within range and almost reaching Alaska. But the joint chiefs said this missile appeared to fly only 480km.
"The military is determining if the missile is a modified Musudan intermediate-range ballistic missile or the shorter range Rodong missile," a military official told the South's Yonhap News Agency.
"I don't think this is designed to respond to Trump, I think this is part of Kim Jong Un's continued efforts to try to advance his programmes," said Jon Wolfsthal, a senior non-proliferation official in former President Barack Obama's Administration now at Harvard's Belfer Centre. "But it has the added effect of calling Trump's bluff. The real question is not what North Korea has done, but what the US is going to do about it," he said.
Some analysts thought the launch could have been the first stages of an intercontinental ballistic missile capable of reaching the United States.
"I think we're all waiting for the first two stages of the ICBM," said Jeffrey Lewis of the Centre for Non-proliferation Studies at the Middlebury Institute of International Studies.
"They finished testing that engine on the stand so now it's time to test it in the air."
Kim Jong Un's regime has declared a goal of producing an inter-continental missile that can deliver a nuclear payload to the US and last year appeared to be making a concerted effort toward achieving that goal. It conducted two nuclear tests and dozens of missile tests, including eight Musudan tests.
Only one, in June, was a success, flying about 400km and reaching a surprisingly high altitude.
But the regime had not fired any since October, perhaps to avoid influencing domestic politics in the US ahead of the presidential election and in South Korea, where the conservative president has been suspended from office and there is now a good chance of a progressive administration that is friendlier to Pyongyang.
In his New Year's address, Kim said that North Korea had test-fired in various ways for a nuclear strike "to cope with the imperialists' nuclear war threats" and said that the country had "entered the final stage of preparation for the test launch of intercontinental ballistic missile".
In response, Trump tweeted: "North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the US. It won't happen!"
However, apart from repeating the usual pledges to work stop North Korea from reaching its nuclear goals, the Trump Administration has said little on what it would do to stop Kim.
The Administration is understood to be embarking on a view of North Korea after eight years in which the Obama Administration practiced "strategic patience" - hoping that it could wait out North Korea.
In Seoul, Acting President Hwang Kyo Ahn convened a meeting of the national security council and said the South Korean Government would work with its allies to ensure a "concerted response to punish North Korea".