Seoul – An advanced US missile defence system will be deployed in a rural farming town in southeastern South Korea, Seoul officials announced on Wednesday, angering not only North Korea and China but also local residents who fear potential health hazards that they believe the US system might cause.As word of the location for the Terminal High-Altitude Area Defence, or THAAD, spread even before the government's formal announcement, thousands of residents in the town of Seongju, the site for the US system, rallied and demanded the government cancel its decision.A group of local leaders wrote letters of complaint in blood and gave them to the Defence Ministry."We oppose with our lives the THAAD deployment," one of the letters said, according to Seongju local council speaker Bae Jae Man, one of the 10 people who wrote the letter.Seoul and Washington officials say they need the missile system to better deal with what they call increasing North Korean military threats. On Monday, North Korea warned it will take unspecified "physical" measures once the location for THAAD is announced.Seoul's Deputy Defence Minister Ryu Je Seung told a news conference that Seongju was picked because it can maximise the THAAD's military effectiveness while satisfying environmental, health and safety standards. He said the defence chiefs of the countries approved the decision.North Korean threatRyu said a THAAD system to be stationed in Seongju by the end of next year would cover up to two-thirds of South Korea's territory from North Korean nuclear and missile threats. No other details were given, although US military bases are in nearby areas.China and Russia oppose the system that they believe helps US radar track missiles in their countries. Seoul and Washington say the system targets only North Korea. Many South Koreans worry China, South Korea's biggest trading partner, might take economic retaliatory measures.Residents in Seongju and several other villages previously rumoured to be candidate sites for the THAAD system have already launched protests, citing fears that the electromagnetic waves that THAAD radar systems emit can possibly cause health problems.Seongju is a town of 45 000 people, and many of them grow yellow melons for a living. South Korean media reported the THAAD system will be placed on a mountain where a South Korea air defence artillery unit is based. About 200 Seongju residents made a protest visit to Seoul's Defence Ministry on Wednesday."You can't make a unilateral decision like this when about half of all Seongju residents live within 2km of where the THAAD system is said to be deployed," Bae said before a meeting with defence officials.Defence officials have disputed this, saying the system will be located on a mountain, not in a residential area, and is harmless if people stay at least 100m away from it.Seoul and Washington launched talks on the THAAD deployment after North Korea conducted a fourth nuclear test and carried about a long-range rocket launch earlier this year.The United States stations about 28 500 troops in South Korea as deterrence against potential aggression from North Korea. China assisted North Korea during the 1950-53 Korean War, while American-led UN troops fought alongside South Korea.