North Korea launches further nuclear tests

North Korea carried out tests in 2006 and 2009

Fotopedia-NASA Goddard ...

The move comes after the isolated state responded defiantly to a unanimous UN resolution which tightened sanctions and condemned a missile test carried out in December last year.

While the country played down its December missile launch as a tribute to the recently deceased "Dear Leader" Kim Jong-il, it has made it clear that the new nuclear test is an act of aggression.

"We are not disguising the fact that the various satellites and long-range rockets that we will fire and the high-level nuclear test we will carry out are targeted at the United States," North Korea's National Defence Commission said.

No explanation about the meaning of "high-level" nuclear tests was provided by the commission, but experts suggest that the phrase used refers to a device made from highly enriched uranium, rather than the plutonium-based devices used in previous tests.