Complex sentence: Recently, The People's Republic of China developed the FT-2000 system to counter AEW and AWACS targets, based on the HQ-9 which is in turn based on the S-300PMU.
Split into simpler sentences: Recently, the People's Republic of China developed the FT-2000 system to counter AEW and AWACS targets. This system is based on the HQ-9, which is in turn based on the S-300PMU.