A top aide to North Korean leader Kim Jong Un arrived in Singapore on Monday night, Japanese public broadcaster NHK said Tuesday, the latest indication that the on-again-off-again summit with US President Donald Trump is going ahead. Meanwhile, the former head of North Korean military intelligence is traveling to New York, according to President Trump, who says Kim Yong Chol is coming to the U.S. to discuss the possible summit with Kim Jong Un. Any diplomatic agreement in which North Korea agreed to give up its nuclear weapons could take as long as 10 years to implement, according to a new analysis from former US officials.