WASHINGTON (Reuters) - White House Chief of Staff John Kelly said on Thursday the Trump administration thinks the threat posed by North Korea s nuclear weapons capability is currently manageable but Pyongyang cannot be allowed to develop the ability to strike the U.S. homeland.  A state that has developed a pretty good ICBM (missile) capability and is developing a pretty good nuclear re-entry vehicle, I would believe ... that that state simply cannot have the ability to reach the homeland,  Kelly said.  Right now we think the threat is manageable but over time if it grows beyond where it is today, well, let s hope that diplomacy works,  said Kelly, a retired Marine Corps general. 