WASHINGTON (AP) — The U.S. intelligence agencies' assessments of the size of North Korea's nuclear arsenal have a wide gap between high and low estimates. Size matters and not knowing makes it harder for the United States to develop a policy for deterrence and defend itself and allies in the region. The secrecy of North Korea's nuclear program, the underground nature of its test explosions and the location of its uranium-enrichment activity has made it historically difficult to assess its capabilities. Some U.S.