(YOMIURI SHIMBUN/ASIA NEWS NETWORK) - The Defence Ministry and the Self-Defence Forces have decided that Japanese P-3C patrol aircraft returning home from anti-piracy activities off the coast of Somalia will give priority to stopping along the way at bases of countries facing the South China Sea, including the Philippines and Vietnam, according to sources.

The P-3C has advanced monitoring capabilities, and the decision is expected to increase the area of the South China Sea that they fly over - areas which China claims as its territory.

It could also be said the move will contribute to the protection of freedom of overflight and allow Japan to support US patrols in its own way, around artificial islands being built by China.

P-3C aircraft belonging to Japan's Maritime Self-Defence Forces (MSDF) participate in multinational efforts to combat piracy off the coast of Somalia, travelling between Japan and Africa about every three months.

Previously, the aircraft refueled at bases relatively far from the South China Sea, in countries including Singapore and Thailand. But while outward journeys will remain the same, return trips will give priority to refueling at bases around the South China Sea, such as those in Vietnam, the Philippines and Malaysia.

The aircraft will also be part of defence-related exchanges in the places visited.

Arrangements are being made for a February stop in Cam Ranh, Vietnam, which is home to a naval base, and to participate in goodwill exercises there.

During Defence Minister Gen Nakatani's visit to Vietnam in November, an agreement was reached to have MSDF ships visit Cam Ranh and to promote defence-related exchanges.

The Philippines' Palawan, located near the Spratly Islands, and Malaysia's Labuan, which faces the southern part of the South China Sea, are also being considered as ports of call.

China has drawn a so-called nine-dash line in the South China Sea and claims sovereignty over the area inside the U-shaped line. It is also constructing artificial islands in the area and working to establish military strongholds on them.

The administration of US President Barack Obama is taking steps to restrain China, including having the Aegis-equipped destroyer USS Lassen sail within 12 nautical miles of an artificial island in October.