North Korea, China and Russia are expanding and diversifying their nuclear weapons stockpiles at a “breakneck” speed, a White House official has said, warning that absent a change in the trajectory of their arsenals, the US may have to increase its own. 

Pranay Vaddi, senior director for arms control, disarmament and non-proliferation at the National Security Council, made the remarks at a forum on Friday, noting that the three countries are driving the US and its allies into bracing for a “world where nuclear competition occurs without numerical constraints”, Yonhap news agency reported.