Complete the following sentence: The islands of the Amur river were subject to some border clashes between Soviet and Japanese forces during the Manchukuo period. <unk> <unk> <unk> <unk>
<unk> <unk> <unk> <unk> <unk> These islands were the site of several military skirmishes during the 1960s.<unk> These islands were the site of several military skirmishes during the 1960s. Most of the disputed islands have been transferred to China.<unk> Most of the disputed islands have been transferred to China. Of the 1,680 islands along the Amur, the agreement now recognizes 902 Chinese islands and 708 Russian islands.