North Korea has expanded a uranium enrichment facility and restarted a reactor that could see it stockpiling enough plutonium to create a nuclear bomb, a U.S. intelligence chief has warned. It comes after Pyongyang announced in 2013 its intention to refurbish and restart its nuclear facilities which it had shut down in 2007 – and began testing long range missiles under the guise of ‘satellite’ launches.

The development marks the pariah nation as one of the main threats facing the U.S. this year, James Clapper, the director of National Intelligence, claimed.

Kim Jong Un (pictured) has restarted North Korea’s nuclear facilities and is weeks away from stockpiling plutonium

Last month North Korea claimed it had conducted its first ‘successful’ hydrogen bomb test. The pictures shown on South Korean TV (above) are file images from nuclear tests by other countries

In an annual assessment by intelligence agencies of the top dangers facing the country, he warned the Senate Armed Services Committee that Kim Jong Un had followed through on his threat.

He said: ‘We assess that North Korea has followed through on its announcement by expanding its Yongbyon enrichment facility and restarting the plutonium production reactor.’

‘We further assess that North Korea has been operating the reactor long enough so that it could begin to recover plutonium from the reactor’s spent fuel within a matter of weeks to months.’ 

Weapons-grade uranium and plutonium are both highly sensitive chemicals that form the key ingredients in the production of nuclear bombs. Both are created artificially, with only a handful of countries in the world – including North Korea – possessing the ability to manufacture them. North Korea does have A-bomb technology: its first three nuclear tests, from 2006 to 2013, were devices on roughly the same scale as the ones used on Hiroshima and Nagasaki.

As late as September last year Pyongyang warned its main nuclear complex was operating and it was working to improve the ‘quality and quantity’ of weapons which it could use against the U.S. at ‘any time’. It comes as it was revealed today U.S. President Barack Obama spoke to Asian allies Japan and South Korea on Monday to garner support for strong action against North Korea in response to the country’s recent weapons tests.

On Sunday, images from North Korean TV (pictured) show a long range rocket being launched over Japan which the country’s state media trumpeted as an ‘epochal event’

North Korean leader Kim Jong-Un watched the rocket launch from a secret planning room

A month ago, it claimed to have carried out its fourth nuclear test with the detonation of a massive hydrogen bomb, though doubts were later cast over the scale and size of the explosion.

Today the White House said Obama had spoken to Japanese Prime Minister Shinzo Abe and South Korean President Park Geun-Hye to weigh the next steps, including a UN Security Council resolution that would bring new sanctions. All three agreed on the need for a ‘strong and united international response to North Korea’s provocations, including through a robust UN Security Council Resolution,’ the White House said.

North Korea carried out a rocket launch as recently as Sunday – weeks after Pyongyang carried out its fourth nuclear test.

Beijing has in the past proved reluctant to support biting multilateral sanctions against North Korea, for fear of destabilizing a regime on China’s border. The White House has said it could introduce unilateral sanctions if necessary, but admits that room to punish the already heavily sanctioned nation is limited.

The US military has also said it wants to send a sophisticated missile defense system to South Korea as quickly as possible.