The US and Britain have ramped up pressure on North Korea after its failed missile launch by warning it must end its "belligerent" behaviour, with one senior US official saying the issue had now "come to a head".
The warnings come after the country's latest missile exploded seconds after it was set off in the early hours of Sunday morning.
US vice president Mike Pence said that the "era of strategic patience" with North Korea is over, while US National Security Adviser HR McMaster said the problem is "coming to a head".
Meanwhile, US President Donald Trump tweeted that the US has "no choice" in the matter.
Mr McMaster said: "This problem is coming to a head. And, so, it's time for us to undertake all actions we can short of a military option to try to resolve this peacefully."
"The president has made clear that he will not accept the United States and its allies and partners in the region being under threat from this hostile regime with nuclear weapons.
"And so we are working together with our allies and partners, and with the Chinese leadership, to develop a range of options."
Foreign Secretary Boris Johnson said: "I strongly condemn the latest North Korean missile launch.
"They must stop these belligerent acts and comply with UN resolutions."
US vice president Mike Pence used an address to American military personnel in South Korea to make it clear Washington would take a tough stance against the regime of Kim Jong Un.
He said: "This morning's provocation from the North is just the latest reminder of the risks each one of you face every day in the defence of the freedom of the people of South Korea and the defence of America in this part of the world.
"This is a challenging time all over the world, but especially here in the Asia-Pacific. But let me assure you, under President Trump's leadership our resolve has never been stronger.
"Our commitment to this historic alliance with the courageous people of South Korea has never been stronger."
The as-yet unidentified missile exploded on launch from a base in Sinpo, a city on the country's east coast, said the US.
Former Conservative foreign secretary Sir Malcom Rifkind said it was possible the missile either malfunctioned or was sabotaged by a US cyber attack.
International concern has been ratcheting up over the deteriorating situation, with China expressing fears war could break out "at any moment".
Japan's Prime Minister Shinzo Abe has said that Japan supports the US in that all options are on the table, and reiterated that pressure and dialogue are necessary in dealing with North Korea.
Speaking to a parliamentary session on Monday, he said: "Needless to say, diplomatic effort is important to maintain peace. But dialogue for the sake of having dialogue is meaningless."
He added "we need to apply pressure on North Korea so they seriously respond to a dialogue" with the international community, and he urged China and Russia to play more constructive roles on the issue.
On Saturday, the North Korean regime gave a huge show of strength with a parade of military hardware feared to have featured a new type of intercontinental ballistic missile.
Despite UN sanctions, North Korea launched a long-range rocket and carried out two nuclear tests in 2016, including its most powerful bomb to date.
There has also been a series of tests of shorter and mid-range rockets in recent years, with varying success.
Donald Trump has previously accused North Korea of "looking for trouble" and warned he was "willing to solve the problem" of the rogue state.
That prompted Korean officials to hit back with a statement saying they would respond to attack.
"We will respond to an all-out war with an all-out war and a nuclear war with our style of a nuclear attack," North Korea's number two official Choe Ryong Hae said.
White House officials appeared to be playing down concerns over the latest test.
One foreign policy adviser said that they had received good intelligence both before and after the launch and that the Trump administration planned no response.
The official said that had it been a nuclear test, "other actions would have been taken by the US".