US military has started deploying the THAAD missile defence system in South Korea, amid high tensions over neighbouring North Korea's nuclear and missile ambitions. China has expressed its serious concern about the move.<br/><br/>The Thaad system is designed to protect against threats from Pyongyang. Hundreds of local residents protested against the deployment, as vehicles carrying equipment arrived at the site in the south of the country.<br/><br/>US has, in recent days, deployed warships and a submarine to the Korean peninsula, amid fears that North Korea could be planning further missile or nuclear tests. The Trump administration, which has been urging China to rein in Pyongyang, is due to hold a classified briefing for senators on the situation at the White House later today.