Full coverage: THAAD Deployment in South Korea

An expert on US-China relations also warns of how this deployment can be a volatile element for the region.

Alek Chance also said the THAAD system has powerful radar which can cover parts of China and Russia's territories for surveillance and information gathering.

He said as the US disregards the discontent from China and Russia, both countries may adopt counter-measures -- including sharing intelligence via their radars to warn each other of potential threats.