Major construction at three of China's large man-made islands in the disputed South China Sea is wrapping up, allowing Beijing to deploy fighter jets and mobile missile launchers to the area at any time, a think tank said Monday.

The building of military and dual-use infrastructure on the so-called Big 3 islands in the contested Spratly chain — Subi, Mischief, and Fiery Cross reefs — is in the final stages, with the naval, air, radar and defensive facilities largely complete, according to the Center for Strategic and International Studies' Asia Maritime Transparency Initiative (AMTI).

All three islands boast hangers that can accommodate 24 fighter jets and four larger planes, including surveillance, transport, refueling or bomber aircraft. Hardened shelters with retractable roofs for mobile missile launchers have also been built on the islands.