The deployment of the Terminal High Altitude Area Defense (THAAD) missile system will have wide ramifications for East Asia and is not a constructive step for regional peace, a US defense and foreign policy expert said.

"South Korea and the US ought to be aware that this decision can have an impact that does not benefit the overall security and the overall peaceful nature of the East Asian system," Ted Carpenter, a senior fellow at the Cato Institute, a US think tank, told Xinhua in an interview.

In July, Seoul and Washington announced an agreement to install one THAAD battery in South Korea by the end of next year, claiming that it was aimed to deter ballistic missiles from the Democratic People's Republic of Korea (DPRK).

China and Russia have expressed strong opposition to the THAAD deployment on the Korean Peninsula as the system far exceeds South Korea's actual defense needs and would directly threaten the strategic security of the two countries.

Carpenter said although the deployment of the THAAD system is primarily aimed at deterring the DPRK and its irresponsible behavior, for some US strategists, a secondary effect is to have a deterrent on China.

"China has every reason to regard that as a hostile act. It is not something that is going to improve bilateral relations between the US and China," he said.

The US expert said China's suspicions about the THAAD system are understandable, as it can have an effect on the Chinese deterrent.

If China sees that the THAAD system can impact Chinese security in an adverse way, Beijing will be suspicious of the deployment and wonder whether the system is directed at China and not simply a deterrent to the DPRK, Carpenter said.

"The US can offer assurances that it is not (directed at China). But again, assurances only go so far when there are facts on the ground," he said.

The decision to deploy THAAD is also another part of the US effort to broaden its bilateral alliance system in East Asia, a move Carpenter believes could be aimed at containing China and also has broader intention beyond that.

"There is no question that the US is encouraging greater integration of its alliances and greater cooperation among its various allies in the region," Carpenter said.

However, he said that South Korea, which desires a cooperative relationship with China, is unlikely to want to become "a cat's paw for the US against China."

"That really does not benefit South Korea in any meaningful way," Carpenter said. "I think if the US is hoping to integrate South Korea into that kind of alliance system, Washington is likely to be disappointed."