Japan will express its wariness over China's muscle-flexing in the South China Sea in this year's defense white paper, warning Beijing's militarization of the disputed waters is making its territorial claims a fait accompli, Kyodo News has learned.

The white paper, which the Cabinet is expected to approve early next month, will say China's activities in the South China Sea could be called high-handed, unilateral action to change the status quo, an outline of the paper obtained by Kyodo News indicates.

The South China Sea remains a source of friction with neighboring countries as China claims sovereignty over most of the sea, which is a vital shipping lane and believed to have rich fishing grounds and possibly large oil or natural gas deposits. Vietnam, the Philippines, Malaysia, Brunei and Taiwan have overlapping claims.