Defense News (unfortunately, no link) has an article providing some additional detail on Chinese efforts to develop an anti-ship ballistic missile. The platform appears to be a DF-21 MRBM (Medium Range Ballistic Missile) which has a range of about 2500 km. The article confirms that terminal guidance of the missile remains the sticking point. A modern ballistic missile with GPS guidance is easily accurate enough to hit an aircraft carrier, but one of the advantages of aircraft carriers over islands is that they move; in the time that it would take to identify the carrier, give the order to launch the missile, and wait for the missile to arrive, the radius of action of a carrier at top speed makes a hit quite unlikely. Thus, the ballistic missile needs some kind of guidance system that will allow it to re-target the aircraft carrier once it re-enters the atmosphere.
The article indicates that the Chinese are aiming at having this capability by 2015. Whether that’s technologically feasible is unclear. Some comments at a previous post on this subject also make the point that China may lack the surveillance and satellite capacity to find carriers at sea in time to actually hit them with missiles; the Defense News article concurs, and notes that China is also making a big investment in such assets, although to date it’s capabilities are still insufficient.
The point of all of this is to increase China’s capability for deterring US intervention in a China-Taiwan dispute, intervention which would rely heavily on aircraft carriers. Anti-ship ballistic missiles are only one part of an arsenal (including air-to-ship missiles, ship-to-ship missiles, and submarines) intended to make the USN nervous about using its carriers anywhere near Taiwan, and consequently to make the US political leadership nervous about intervening. This doesn’t mean that the Chinese intend to seize Taiwan at any specific time in the future, but it does mean that the Chinese leadership believes that such a seizure may at some point be necessary.