Simplify the following text for a Grade 9 native English-speaking person.
Original: The Russian government responded by capturing and executing Triapitsyn ; however , the Japanese government felt that this was not sufficient , and used the incident as an excuse to occupy the northern half of Sakhalin island , and to delay diplomatic recognition of the Soviet Union until 1925 .
Simplified: The government of Russia responded by murdering Triapitsyn ; however , the Japanese government felt that this did n't make up for what had happened . Japan used this as an excuse to have it residents live in Sakhalin island , where they remained till 1925 .