Many of them were apprehended and interned either in camps or at the grounds of their respective legations (or embassies) until they could be repatriated by neutral powers.

The US state department negotiated with Japan regarding the repatriation of its (and other Allied nations) nationals through the diplomatic representatives of Spain and chartered the M/S Gripsholm and the S/S Drottningholm passenger ships from the Swedish American Line, as they were neutral ships (and stuck outside the British and German blockade of the North Sea and thus unable to return to Sweden), to handle the repatriation of citizens of the US and other countries at war with the Japanese (in the case of S/S Drottningholm, with Italy and Germany). The first repatriation happened in 1942. In June 1942, M/S Gripsholm took aboard interned Japanese diplomats and civilians in New York, sailed to Rio de Janeiro to board more Japanese nationals and then sailed to Portuguese Mozambique to meet up with the Japanese passenger ship Asama Maru, which was carrying American, Canadian, British, French and Dutch civilians and diplomats from Japan, Hong Kong, Singapore, the Phillines and French Indochina (Vietnam).

The Swedish American Line prided itself on having an excellent kitchen aboard, which was put to work during the repatriation travels, as many of the Allied nationals had been served bad or insufficient food by the Japanese while in internment or onboard the repatriation ships. Here's the lunch menu for the 17th of August and here's the three-course dinner menu aboard for the 23rd of August 1942 while heading back from Mozambique.

Reportedly, the passengers of the Teia Maru (another Japanese ship met to exchange nationals in October1943) had to bribe the crew for basic service, were over-crowded and served really bad food and the much better food on the M/S Gripsholm was appreciated both by the outgoing Japanese nationals and the incoming nationals of the Allied nations.

M/S Gripsholm, here in her wartime white painting, with blue and yellow striped for the neutral Swedish national colours and prominent markings wouuld sail with those markings lit up by powerful lights at night to avoid attacks by submarines,and with the approval of all sides. She sailed on Japan while S/S Drottningholm sailed on Germany and Italy. Both ships would complete 33 cruises to repatriate diplomatic staff and civilians and exchange wounded prisoners of war during the war and return prisoners of war immediately after the war.