North Korea announced on Wednesday that it has successfully conducted a hydrogen bomb test. The confirmation came after South Korean officials detected an "artificial earthquake" near North Korea's main nuclear test site on Wednesday, reported AP. A United Nations agency said that a confirmed test would be a "grave threat to international peace and security".

A hydrogen bomb is more powerful than plutonium weapons, which is what North Korea used in its past nuclear tests, reported CNN. "If there's no invasion on our sovereignty we will not use nuclear weapon," the North Korean state news agency said. "This H-bomb test brings us to a higher level of nuclear power."

While the United States said it would take days to determine whether the H-bomb test was indeed successful, Wednesday's development did not come as a surprise. North Korean leader Kim Jong-un had said last month that his country has the capacity to launch a hydrogen bomb. However, North Korea hadn't conducted an atomic explosion since early 2013.