According to information obtained by Savannah River Site Watch, the United States is in the process of repatriating U.S.-origin plutonium from Germany, Switzerland, and Japan. On February 14, 2016, Oceanic Pintail, a U.K.-flagged ship dedicated to transport of nuclear materials, arrived in the port of Charleston, South Carolina. The ship is believed to carry U.S.-origin plutonium from Germany and Switzerland. Umweltaktivisten.de, a German-based environmental group, believes that the shipment may contain 30 kgs of plutonium in Germany and 18 kgs in Switzerland that the United States was planning to bring to the Savannah River Site.
In its most recent INFCIRC/549 report to the IAEA, Switzerland declared having "less than 50 kg" of separated plutonium as of 31 December 2014. Germany reported having a much larger amount - 2.1 tons - most of which, however, is German-origin.
Two nuclear transport ships, Pacific Heron and Pacific Egret, are reported to be on their way to collect plutonium from Japan. The material is question is the 331 kg of plutonium that was supplied to Japan by the United States, the United Kingdom, and France to fuel the Fast Critical Assembly. The agreement to transfer this plutonium to the United States was reached in March 2014.
UPDATE 03/01/2016: According to a press-release issued by the Swiss government, the shipment included "about 20 kg of plutonium [...] that had been stored on the site of today's Paul Scherrer Institute (PSI) since the 1960s. The plutonium came from reprocessed fuel rods of the Diorit research reactor that operated from 1960 to 1977."