Wall Street Journal:
China’s top nuclear experts have increased their estimates of North Korea’s nuclear weapons production well beyond most previous U.S. figures, suggesting Pyongyang can make enough warheads to threaten regional security for the U.S. and its allies.
The latest Chinese estimates, relayed in a closed-door meeting with U.S. nuclear specialists, showed that North Korea may already have 20 warheads, as well as the capability of producing enough weapons-grade uranium to double its arsenal by next year, according to people briefed on the matter.
A well-stocked nuclear armory in North Korea ramps up security fears in Japan and South Korea, neighboring U.S. allies that could seek their own nuclear weapons in defense. Washington has mutual defense treaties with Seoul and Tokyo, which mean an attack on South Korea or Japan is regarded as an attack on the U.S.
“I’m concerned that by 20, they actually have a nuclear arsenal,” saidSiegfried Hecker, a Stanford University professor and former head of the Los Alamos National Laboratory, who attended the closed-door meeting in February. “The more they believe they have a fully functional nuclear arsenal and deterrent, the more difficult it’s going to be to walk them back from that.”
Chinese experts now believe North Korea has a greater domestic capacity to enrich uranium than previously thought, Mr. Hecker said.
The Chinese estimates reflect growing concern in Beijing over North Korea’s weapons program and what they see as U.S. inaction while President Barack Obama focuses on a nuclear deal with Iran.
A well-armed North Korea may prompt the U.S. to adopt countermeasures, especially in missile defense. Adm. William Gortney, head of U.S. Northern Command, said this month that defense officials believe North Korea can now mount a nuclear warhead on an intercontinental ballistic missile called the KN-08. U.S. officials don’t believe the missile has been tested, but experts estimate it has a range of about 5,600 miles—within reach of the western edge of the continental U.S., including California…