Chinese military experts says North Korea may have DOUBLE the number of nuclear weapons

North Korea may already have 20 nuclear warheads - double as many as previously thought, Chinese nuclear experts have warned.  The pariah state may also have the capability to produce enough weapons-grade uranium to double its arsenal by next year, The Wall Street Journal has reported. 

Chinese estimates of Pyongyang's nuclear production, relayed to US nuclear specialists, exceed most previous US forecasts of between 10 to 16 bombs, said the report, which cited people briefed on the matter.