Reopening talks with North Korea is the only way for the administration of US President Donald Trump to head off the specter of the communist nation perfecting its capabilities to strike the continental US with nuclear weapons, a US expert said Tuesday.Leon Sigal, director of the Northeast Asia Cooperative Security Project at the Social Science Research Council in New York, made the appeal in a CNN op-ed piece, arguing that neither sanctions nor Chinese pressure will curb Pyongyang's nuclear and