Seismic jolt likely a nuclear test
SEOUL — North Korea carried out its sixth nuclear test Sunday, according to the South Korean military, an extraordinary show of defiance by North Korea’s leader, Kim Jong Un, against President Trump.
A seismic tremor detected at 12:36 p.m. local time, emanating from the Punggye-ri underground nuclear test site in northwestern North Korea, set off a scramble to determine whether the North had carried out another test. The South’s military soon confirmed that it had.
The Defense Ministry estimated that the tremor had a magnitude of 5.7, revising an earlier estimate of 5.6. But the U.S. Geological Survey’s estimate was much higher, at 6.3.
The test came just days after North Korea fired a ballistic missile over Japan, sharply escalating tensions in the region. And just hours earlier, the North claimed that it had developed a hydrogen bomb that could be mounted on an intercontinental ballistic missile, although it offered no real evidence for that.
Trump has warned he would unleash “fire and fury” against North Korea if Pyongyang continued to threaten the United States with nuclear missiles.
President Moon Jae-in of South Korea and Prime Minister Shinzo Abe of Japan called emergency meetings of their national security councils after the tremor was detected. “If North Korea has conducted a nuclear test, we can never accept that,” Abe told reporters.
Hours before the tremor was detected Sunday, North Korea’s state news agency said the country had developed a hydrogen bomb that could be mounted on an intercontinental ballistic missile. The report offered no evidence for the claim, other than photos of Kim inspecting what it said was the weapon.
The report said Kim had visited the Nuclear Weapons Institute, which the news agency said had recently “succeeded in a more developed nuke” and in “bringing about a signal turn in nuclear weaponization.”
It was unclear whether such a weapon may have been tested Sunday. Even South Korea’s estimate of a 5.7 magnitude tremor would make the blast considerably larger than the North’s previous one last September, which set off a tremor with an estimated magnitude of 5.2.
Trump’s aides have concluded that his options in responding to a North Korean nuclear blast are limited. A strike on the North’s main nuclear and missile sites faces the same challenge it always has: the North’s ability to retaliate against Seoul, the South’s capital, which is within range of its artillery.
So for now, Trump has turned to the same strategy his predecessors have tried: increasing economic pressure and threatening force.
Another strategic consideration in responding to a nuclear blast is China, which for decades has been the North’s closest ally. While China’s president, Xi Jinping, fears that a collapse in North Korea could lead to a wave of hungry refugees and a scramble for North Korea’s territory and nuclear weapons, he appears to have lost patience with Kim.