North Korea's releases video showing 'nuclear attack' on Washington DC

North Korean leader Kim Jong. Photo / AP

North Korea detonates a sea-launched nuclear missile over Washington DC, obliterating the US Capitol building and the White House, in a fantasy video released by the Ministry of Propaganda.

Pyongyang released the blood-curdling production as tensions continued to simmer on the Korean Peninsula following this month's annual joint US military exercises with South Korea.

The four-minute video shows computer-generated images of a submarine-launched missile bursting into the sky, entering the earth's upper atmosphere and then returning to earth to strike the US capital.

As the US Capitol first totters and explodes a message flashes up on the screen in Korean: "If US imperialists budge an inch toward us, we will immediately hit them with nuclear weapons." The video montage concluded with the US flag hanging tattered and in flames.

North Korea tested its first nuclear weapon in 2006 but was believed to be a long way from being able to miniaturise a device to fit on a ballistic missile.

However fresh intelligence assessments this month have indicated that Pyongyang may now be close to miniaturising a weapon.

David Albright of the Institute for Science and International Security and a leading expert on nuclear proliferation has said his group believes North Korea has probably already miniaturized a warhead.

Pyongyang carried out its fourth nuclear test in January - allegedly of a more powerful hydrogen device - and conducted a satellite rocket launch a month later that was widely seen as a disguised ballistic missile test.

This would be a key step towards the North's dream of being able to strike directly at the west coast US, although that would still require advances in missile and weapons technology that are believe to be years away.

The video was published on the North's propaganda website DPRK Today and also showed images from the Korean War, including dead and surrendering US airmen, and the capture of US spy ship Pueblo in 1968.

Pyongyang has upped the rhetorical ante in recent weeks, with near daily threats of nuclear and conventional strikes against the South and the US mainland in response to large-scale South-US war games.

The threats have turned increasingly personal, and North Korea leader Kim Jong-Un last week watched a live-fire long-range artillery drill simulating a strike on the official residence of his South Korean counterpart, the Blue House.

North Korea has been pushing to acquire submarine-launched ballistic missile (SLBM) capability which would take its nuclear strike threat to a new level, allowing deployment far beyond the Korean peninsula and the potential to retaliate in the event of a nuclear attack.

The North has conducted a number of what it says were successful tests of a SLBM, but experts have questioned the veracity of those tests, suggesting Pyongyang had gone little further than a "pop-up" test from a submerged platform.