A British vessel Pacific Egret, has left Japan on 22 March 2016 carrying 331 kg of plutonium from the Fast Critical Assembly (FCA) in JAERI Tokai Research Establishment. The material is being transferred to the Savannah River Site in the United States, where it will be prepared for final disposition. The agreement to transfer the plutonium, most of which was supplied by the United Kingdom, as well as HEU, was reached in March 2014.
The exact disposition path for the plutonium is unknown. The plan to bring the material to the Savannah River Site has met significant local opposition. According to Tom Clements, director of SRS Watch, "the U.S. Government has done a poor job of explaining why this material is being taken to SRS." The governor of South Carolina has written a letter to the Secretary of Energy, demanding a shipment of weapons-grade plutonium en route to her state from Japan be turned back or sent elsewhere.
It is also important to note that while the plutonium was placed under IAEA safeguards while it was in Japan, the United States does not appear to have a plan to apply IAEA safeguards to the material.
UPDATE 04/01/2016: According to a statement made at the 2016 Nuclear Security Summit, all HEU has been removed from the FCA as well.
UPDATE 01/13/2017: According to the NNSA 2016 Report, the total amount of material removed from the Fast Critical Assembly was "over 500 kilograms." This suggests that the amount of HEU in the shipment was at least 170 kg, which is consistent with the information about 199.5 kg of HEU at the beginning of FCA operations.