An underwater-launched missile lifts off in the waters off North Korea's eastern coastal town of Wonsan.
North Korea confirmed Thursday it tested a new submarine-launched ballistic missile, calling it a “significant achievement” in its efforts to contain external threats and bolster its military power.
The test-firing Wednesday was North Korea’s first of a submarine-launched missile in three years and came ahead of a weekend resumption of nuclear diplomacy with the United States. Some experts say North Korea wants to show to the U.S. what would happen if diplomacy fails again.
The Korean Central News Agency said the test of the Pukguksong-3 missile in the waters off its east coast was successful and “ushered in a new phase in containing the outside forces’ threat to (North Korea) and further bolstering its military muscle for self-defense.”
An underwater-launched missile lifts off in the waters off North Korea's eastern coastal town of Wonsan. 
It didn’t say which outside forces threaten its security. But North Korea has previously said it was forced to develop nuclear-armed missiles to cope with U.S. military threats.
North Korean and U.S. officials are to meet on Saturday to restart diplomacy on how to end the North Korean nuclear crisis. That diplomacy largely remains stalemated after the February breakdown of a second summit between President Donald Trump and North Korean leader Kim Jong Un in Vietnam.
North Korea has recently warned its dealings with the United States may end if it fails to come up with new proposals to salvage the nuclear diplomacy by December.
KCNA said the missile was launched in a vertical mode and that its test had no adverse impact on the security of neighboring countries. It said Kim sent “warm congratulations” to the national defense scientific research units involved in the test-firing.
The KCNA report didn’t elaborate on whether the missile was fired from a submarine, a barge or other underwater launch platform.
Pukguksong, or Polaris, is a solid-fuel missile in the North’s weapons arsenal. The country first test-launched a Pukguksong-1 missile from an underwater platform in 2016, and Kim said at the time his military had gained “perfect nuclear-attack capability.” A year later, the North test-launched a Pukguksong-2, a land-based variant of the missile.
North Korea having an ability to fire a missile from a submarine is a threat to the United States and its allies because such launches are harder to detect early enough to respond. The use of solid fuel also increases a weapon’s mobility.
After Wednesday’s launch, the U.S. State Department called on North Korea “to refrain from provocations, abide by their obligations under U.N. Security Council resolutions, and remain engaged in substantive and sustained negotiations to do their part to ensure peace and stability on the Korean Peninsula and achieve denuclearization.”
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