North Korea’s failed missile test was an attempt to “provoke something”, US Defence Secretary James Mattis says.
The missile fired on Sunday blew up almost immediately, the Pentagon said.
The US would work with China to reduce tensions, Mr Mattis added. He spoke after heated rhetoric from both sides.
On Monday Vice-Foreign Minister Han Song-ryol told the BBC that North Korea could test missiles on a weekly basis and warned of “all-out war” if the US took military action.
“If the US is planning a military attack against us, we will react with a nuclear pre-emptive strike by our own style and method,” Mr Han said.
Meanwhile a report in the Guardian newspaper quoted unnamed officials as saying the US was considering shooting down North Korean missile tests as a show of strength.
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Mr Mattis said Sunday’s missile test had not involved an intercontinental ballistic missile but had still been reckless.
“It shows why we are working so closely right now with the Chinese… to try to get this under control and aim for the denuclearized Korean peninsula,” he said.
China has criticised North Korea’s missile tests. In February it banned imports of North Korean coal and reports in Chinese media have raised the possibility of restricting shipments of oil to the isolated North if the tests continue.
The US is also threatening tougher economic sanctions that could include an oil embargo, a global ban on North Korea’s airline, intercepting cargo ships and punishing Chinese banks that do business with the country, Reuters news agency reported.
How did we get here?
North Korea has accelerated its nuclear and missile tests in recent years, despite international condemnation and UN sanctions.
Its aim is to be able to put a nuclear warhead on an intercontinental ballistic missile that can reach targets around the world, including the US.
US President Donald Trump has said that will not happen, and stepped up pressure on the isolated North.
He has sent a navy strike group towards the Korean Peninsula, and the US and South Korea are moving ahead with the early deployment of a controversial missile defence system.
Despite the tension, North Korea may carry out a sixth nuclear test soon, observers say.
What has the US told North Korea?
US Vice-President Mike Pence has said North Korea should not test US President Donald Trump, whose “strength and resolve” had been shown by missile and bomb attacks in Syria and Afghanistan.
On Monday, in South Korea, he said that the US policy of “strategic patience” with North Korea was over and reiterated US support for South Korea.
Last month, US Secretary of State Rex Tillerson warned that pre-emptive military action was “on the table”.
What does North Korea say?
Vice-Foreign Minister Han Song-ryol told the BBC that North Korea believed its nuclear weapons “protect” it from the threat of US military action.
The North fears the US and South Korea could use force in an attempt to overthrow the regime of Kim Jong-un.
At the UN on Monday, North Korea’s permanent representative Ambassador Kim In-ryong, condemned the US missile strikes in Syria, which targeted an air base after a suspected chemical attack by the government.
He said the US was “disturbing global peace and stability and insisting on the gangster-like logic that its invasion of a sovereign state is decisive and just and proportionate and contributes to defending the international order”.
And what about other world powers?
Chinese Foreign Ministry spokesman Lu Kang told reporters in Beijing on Monday that the Korean peninsula was “highly sensitive, complicated and high risk” and that all sides should “avoid taking provocative actions that pour oil on the fire”.
Russia’s Foreign Minister Sergei Lavrov said Moscow would not tolerate “missile adventures by Pyongyang” but a unilateral use of power by the US would be “a very risky course”.
Japanese Prime Minister Shinzo Abe on Monday told a parliamentary session that diplomatic efforts were “important to maintain peace”, but “dialogue for the sake of having dialogue is meaningless”.