The official pointed to a recent exchange of letters between Trump and Kim as a positive sign, adding that although the date and location of the summit have yet to be determined, it could take place "sometime later this year."

The UN Security Council adopted US-backed guidelines Monday to facilitate the delivery of humanitarian aid to North Korea. A US official said that the new procedures are solely intended to establish a clear and uniform process to review legitimate humanitarian exemption requests and guard against any activities that would undermine existing Security Council resolutions. The new procedures are intended to allow international non-governmental organizations to carry out relief activities in North Korea "for the benefit of the civilian population.”