It is the continuing tension on the Korean Peninsula, and news agency Reuters is quoting an anonymous source as saying the DPRK is preparing to stage one or two more nuclear tests this year, as well as a rocket launch.

Reuters says the move is part of an effort by the DPRK to force the United States into diplomatic talks. There had been speculation that the DPRK might launch another rocket on Saturday, to mark the 71st birthday of its late leader Kim Jong Il.

But those fears proved to be unfounded, and no such launch was carried out. On Tuesday, the DPRK said it had successfully conducted a third underground nuclear test. The UN Security Council strongly condemned the move, calling it "a grave violation" of UN resolutions. In December, the country launched a rocket, which also triggered international condemnation.