The final test series concluded in the spring and summer of 1996. According to Japanese government sources (reported in Nihon Keizai Shimbun), the penultimate underground Chinese nuclear test on 8 June 1996 (calculated at 20 to 80 kilotons) was actually a simultaneous detonation of multiple warheads (a common practice by both the U.S. and USSR). It was said to be part of a program to produce smaller warheads for submarine-launched and multiple-targeted missiles. Overall, the yields since 1990 have suggested that two warheads have been in development: one in the 100-300 kt range, and one in the 600-700 kt range.
China's last nuclear test was detonated at 0149 GMT (9:49 p.m. EDT) on 29 July 1996. According to the Australia Geological Survey Organization in Canberra its yield was 1 to 5 kilotons, with a seismic magnitude of Mb 4.3. This was China's 45th test, and its 22nd underground one.
It is believed that with the conclusion of this series, China has completed development of a range of warheads similar to the state of the art weapons developed by the other major nuclear powers. These would be miniaturized hardened thermonuclear warheads with yields in the tens to hundreds of kilotons, as well as warheads with variable yield options, and enhanced radiation ("neutron bomb") warhead.
about asat and midcourse for last 3 yrs, i guess this was the time they were waiting for. 
