North Korea will continue to test missiles, a senior official has told the BBC in Pyongyang, despite international condemnation and growing military tensions with the US.
"We'll be conducting more missile tests on a weekly, monthly and yearly basis," Vice-Foreign Minister Han Song-ryol told the BBC's John Sudworth.
He said that an "all-out war" would result if the US took military action.
Earlier, US Vice-President Mike Pence warned North Korea not to test the US.
He said his country's "era of strategic patience" with North Korea was over.
Mr Pence arrived in Seoul on Sunday hours after North Korea carried out a failed missile launch.
Tensions have been escalating on the peninsula, with heated rhetoric from both North Korea and the US.
Mr Han told the BBC: "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."
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. It test-fired a missile on Sunday that exploded within seconds of launch, following a grand military parade on Saturday.