China's first aircraft carrier entered service on Tuesday, but since it still has no planes aboard, the only primary use of the vessel is a signal of China's growing naval might. The Liaoning, as the carrier is called, has been in sea trials since last August, built on the retrofitted hull of the Soviet-made Varyag, which China bought from the Ukraine. The closest thing Japan has to an aircraft carrier is a helicopter-carrying destroyer, so the commissioning of the Liaoning represents a significant, if for now sympbolic, advance in Chinese naval power against its rival. The Associated Press points out that a working air wing is still a long way off: "It will take years to build the proper aircraft, to train pilots to land in adverse weather on a moving deck, and to develop a proper carrier battle group." In the meantime, the ship is expected to be used mostly for research and training. But the ship's launch does "raise the overall operational strength of the Chinese navy," the Defense Ministry has said. The timing of that move is everything.