North Korea's nuclear test in defiance of the U.N. resolutions has drawn strong reactions from the world leaders including its only strong ally China.
U.S. President Barack Obama said that North's nuclear test Tuesday was a threat and a provocation.
Pyongyang Tuesday termed the underground explosion that caused a tremor of 4.9 magnitude as an act of self-defence against "U.S. hostility" and warned of further steps if necessary.
This put pressure on U.S. President Barack Obama on the day he was to give his State of the Union speech.
"Provocations of this sort we saw last night will only isolate them further, as we stand by our allies, strengthen our own missile defence, and lead the world in taking firm action in response to these threats," Obama said in his speech.
Korean Central News Agency said after conducting the test Tuesday, "The nuclear test was conducted as part of measures to protect our national security and sovereignty against the reckless hostility of the United States that violated our republic's right for a peaceful satellite launch."
Although North Korea also conducted the nuclear tests in 2006 and 2009 and launched the long range rocket last year, it is not believed that it has manufactured a nuclear missile capable of reaching the U.S.
Washington believes that North's ultimate aim is to create a nuclear ballistic missile targeting the United States in what North calls "high intensity, all-out action."
China, which has been North Korea's only major ally for years, has also condemned the latest nuclear test Tuesday.
In the emergency meeting held by the U.N. Security Council, the Council "strongly condemned" the nuclear test and pledged to take appropriate measures in response.
Kim Jong-un is the third in line to rule the country and has initiated two long-range rocket launches and a nuclear test during the first year of his rule.
Reactions From Across the Globe
Chinese Foreign Minister Yang Jiechi said that the country had become "strongly dissatisfied and resolutely opposed" to North Korea's nuclear test and has urged North to "Stop any rhetoric or acts that could worsen situations and return to the right course of dialogue and consultation as soon as possible."
The U.N. Security Council called North's act a "grave violation" of the U.N. resolutions.
"In line with this commitment and the gravity of this violation, the members of the security Council will begin work immediately on appropriate measures in a Security Council resolution," the council said in its emergency meeting held hours after the test.
U.S President Barack Obama and South Korea president Lee Myong-bak spoke telephone and pledged to "seek a range of measures aimed at impeding North Korea's nuclear and ballistic missile programs and reducing the risk of proliferation," the White House said in a statement.
Japanese Prime Minister Shinzo Abe called the test a "grave threat" that will not be accepted, Reuters has reported.
According to the report, Russian Foreign Minister Sergei Lavrov too urged North Korea to stop advancing its nuclear talk and start negotiations. NATO has also called it as an "irresponsible act."
Meanwhile, the resolute North Korea's Foreign Ministry said in a statement broadcast by its official KCNA news agency, "If the United States continues to come out with hostility and complicates the situation, we will be forced to take stronger, second and third responses in consecutive steps."
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