Even North Korea's closest ally is getting very worried about the country's nuclear arsenal—which may be a lot bigger than we thought. China has warned American nuclear experts that Pyongyang now has around 20 nuclear warheads, and the country has become so good at enriching uranium that it could double that number by the end of next year, sources tell the Wall Street Journal. The number of warheads China now believes its neighbor has is a lot higher than previous estimates and could make it tougher to talk Pyongyang into getting rid of the arsenal, the Guardian reports.
"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," former Los Alamos National Laboratory chief Siegfried Hecker, who was present at the February meeting with Chinese nuclear experts, tells the Journal. China still has strong ties to North Korea, though relations have gone downhill since Kim Jong Un took charge, the Journal notes. But China isn't North Korea's only friend: Russia announced yesterday that Kim will meet Vladimir Putin during a visit to Moscow next month that will be the North Korean leader's first official trip abroad, CNN reports. (Read more China stories.)