A senior US justice official accused China on Thursday of helping North Korea launder money from massive cyber thefts it has carried out to raise funds in the face of international sanctions.At an event hosted by a Washington think tank, John Demers, the assistant attorney general for national security, also said North Korea was likely to be getting support from China in the form of cyber expertise and training.“The other thing … that really pops out of our cases … is the involvement of China…