In March, the North warned it would not rule out a "new form"
of nuclear test to boost its nuclear deterrent, after the U.N.
Security Council condemned Pyongyang's launch of a mid-range
ballistic missile into the sea east of the peninsula.
North Korea has been under U.N. sanctions since its first
nuclear test in 2006, banning it from conducting atomic and
missile tests, barring U.N. member states from weapons trade
with Pyongyang and financial transactions that facilitate them.
It regularly threatens the United States and South Korea with
(Writing by Nick Macfie)
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