SEOUL North Korea fired up to two short-range missiles off its west coast on Thursday, Yonhap news agency quoted government officials as saying, the second launch in as many weeks, drawing quick criticism from the United States.
A South Korean defence ministry official confirmed the reclusive state had fired at least one missile, but could not specify the exact number or type.
White House National Security spokesman Gordon Johndroe said that North Korea's missile test activity was "not constructive" and Pyongyang should focus on dismantling its nuclear programme.
Pyongyang has refused to implement a February 13 deal with South Korea, the United States, Russia, China and Japan under which it agreed to begin shutting down its nuclear programmes in return for energy aid.
"The United States and our allies believe that North Korea should refrain from testing missiles," Johndroe said in a statement to reporters on the sidelines of a Group of Eight summit in Heiligendamm, Germany.
"We have confirmed that the North has fired a missile," a South Korean defence ministry official told Reuters, adding it appeared to be part of regular military exercises.
In late May, the North fired a short-range surface-to-ship missile off its east coast. Both South Korean and U.S. officials dismissed the launch as part of regular military drills.
Asked about the most recent apparent launch, a Japanese Defence Ministry official told Reuters: "I am aware of the report but we have not been able to confirm it. Even if it is true, I don't think it poses a grave threat to the security of neighbouring countries including Japan."
Yonhap quoted a South Korean government official as saying: "We suspect the number of missiles fired today was one or two. We are working to distinguish the types of missiles."
Normally, missiles fired off the west coast would land in the Yellow Sea which lies between the Korean peninsula and China.
"Last month when the North fired one missile off the east coast, it had also tried to do the same thing off the west coast," Yonhap quoted the South Korean government official as saying.
"It seems like they fired those which they had not fired at the time."
North Korea fired a barrage of long and short range missiles last year, triggering United Nations sanctions. It drew more punitive measures with its first nuclear test in October.
Military experts have voiced concern about the North's firing of long range missiles, which could carry a nuclear warhead to Alaska or possibly the continental United States.
U.S. President George W. Bush and Japanese Prime Minister Shinzo Abe, speaking with reporters on Wednesday before a bilateral meeting at the summit, said they were united in wanting North Korea to move ahead on disarmament.
South Korea has withheld critical food aid to the North until the reclusive communist state begins implementing the February disarmament deal.
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