North Korea is operating at least 13 undeclared bases to hide mobile, nuclear-capable missiles, a new study released Monday has found, raising fresh doubts over US President Donald Trump’s signature foreign policy initiative. Trump has hailed his July summit with North Korean leader Kim Jong Un as having opened the way to denuclearization of the divided peninsula, defusing tensions that less than a year ago brought the two countries to the brink of conflict. Since the summit in Singapore, North Korea has halted nuclear and missile tests dismantled a missile test site and promised to also break up the country’s main nuclear complex. But researchers at the Center for Strategic and International Studies in Washington said they have located 13 missile operating bases that have not been declared by the government, and that there may be as many as 20. “It’s not like these bases have been frozen,” Victor Cha, who leads CSIS’s North Korea program, told The New York Times, which f...