The comments by Wang Hongguang came as a South Korean court's decision to uphold the impeachment of Park Geun-hye, the country's former president, fanned hopes Seoul might put plans for the Terminal High Altitude Area Defence system on hold.
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Wang, former deputy commander of the Nanjing Military Region, said China could not take the chance the next South Korean president would change policy and roll back the deployment.
The first THAAD components arrived at the Osan Air Base in South Korea last week.
Wang said Beijing had measures in place to neutralise THAAD's radars. "We will complete our deployment before THAAD begins operations. There is no need to wait for two months [before the election of the next South Korean president]," he said on the sidelines of the political sessions in Beijing. "We already have such equipment in place. We just have to move it to the right spot."
Yue Gang, a military commentator and former People's Liberation Army colonel, said China could either destroy THAAD or neutralise it.
"Destroying [THAAD] should only be an option during wartime," Yue said.
But China could interfere with the system's functions through electromagnetic technology, he said.
Yue said an ideal place to install the Chinese equipment was on the Shandong peninsula on the country's east coast, opposite South Korea.
Fu Qianshao, an aviation equipment expert with the PLA Air Force, said China could also send planes – manned or unmanned – to fly close to THAAD to interfere with its radar signals. All the country's armed forces had the capacity to interfere with radar signals, Fu said.
Wang said China's chief concern was not just with South Korea's deployment of the American system but also the United States' broader potential to contain the region in a sophisticated web of missile defence systems in Japan, Singapore, the Philippines and even Taiwan.
The THAAD system consists of a sophisticated radar and interceptor missiles designed to spot and knock out incoming ballistic missiles.