http://gizmodo.com/5928295/chinas-df+21d-missile-is-a-one+shot-aircraft-carrier-killer
"The DF-21D (Dong-Feng 21 variant D) is the world's first and only anti-ship ballistic missile (ASBM). It's a two stage, land-launched missile with a maximum estimated range of 2,700 to 3,000 km. Its single fuel-air explosive warhead packs 200 to 500 kilotons. It was developed by China Changfeng Mechanics and Electronics Technology Academy as part of the country's massive military modernization effort, an initiative focused primarily on developing overwhelming missile technologies for which there are no effective defenses. The Defense Department believes it entered active service around 2009."
The yield is wrong. The biggest conventional bomb is the Russian FOAB at 40 tons of tnt. Half a megaton is a sizable nuke.
200-500kt is the yield for the nuclear armed DF-21. Not sure what the non-nuclear payload/yield would be. I couldn't find anything definitive. A lot about the DF-21D is still speculative.