Several warships have already been seen using the facility, which can also accommodate landing craft, according to the sources. It is reported that the islets have an advanced radar system in place and a heliport for use by aircraft carrier-based helicopters.
The move was apparently aimed at boosting China's preparedness for possible future confrontations with Japan and the US. Both Tokyo and Washington have shown concern over Beijing's growing maritime assertiveness.
China has intensified monitoring of the air defense identification zone it declared over the sea in 2013, which hasn't been recognized by Japan or the US.
The confrontation between the two neighbors over the East China Sea commenced following the end of the World War II, when Tokyo occupied large swaths of Chinese lands.
The reigniting of tensions follows a ruling of the Hague-based Permanent Court of Arbitration on a territorial dispute in the South China Sea. The recent order stated that Beijing has no historical rights for areas it claims. Beijing has refused to recognize the legitimacy of the court.
