U.S. may hold fire on 'non-threatening' N Korea missiles

The North also has a "considerable" ability to produce weapons based on highly enriched uranium, it said in a two-yearly White Paper.

Mr Carter said on Tuesday in his final press briefing that if a North Korean long-range missile is ever deemed to be threatening, "it will be intercepted".

North Korea has conducted two nuclear tests over the past year - five in total - raising fears that it has made significant nuclear advances. The ministry was unable to estimate weapons-grade uranium stocks, citing difficulties in penetrating the North's secretive uranium program.

In 2016, North Korea conducted two nuclear tests and numerous missile launches in its quest to develop a nuclear weapons system capable of hitting the U.S. mainland.

USA think tank the Institute for Science and International Security estimated in June that the North's total nuclear arsenal stood at more than 21 bombs - up from 10-16 weapons in 2014 - based on estimates of the country's plutonium and uranium stocks.

North Korea deactivated the Yongbyon reactor in 2007 under an aid-for-disarmament deal.

North Korean dictator Kim Jong Un recently threatened to test a nuclear capable intercontinental ballistic missile.

Last August, North Korea confirmed it had restarted the production of plutonium in the country, following speculations it reopened its Yongbyon nuclear facility that month. The type of plutonium needed for a nuclear bomb is typically extracted from spent nuclear reactor fuel.

Kim Jong-un smiles as he visits Sohae Space Center in Cholsan County, North Pyongan province for the testing of a new engine for an intercontinental ballistic missile (ICBM) in this undated photo released April 9, 2016.

Trump has vowed that North Korea would never be allowed to fulfill its threat to test an ICBM that could reach the US.

On Sunday, North Korea's foreign ministry said the country developed the ICBM to fortify its self-defense capabilities to counter "the ever more undisguised nuclear war threat from the US", according to the North's official Korean Central News Agency.

  • Jon Douglas