Given the task definition and input, reply with output. In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Troops work for the?, Context: At the end of World War II Soviet troops occupied southern Sakhalin Island and the Kuril Islands, making them part of the RSFSR. The status of the southernmost Kurils remains in dispute with Japan.
RSFSR