SEOUL -- The decision between South Korea and the United States to deploy the Terminal High Altitude Area Defense (THAAD) on Friday triggered various controversies as it causes regional tensions and strong oppositions from people living in candidate sites amid remaining doubts about its military effectiveness.

Military authorities of the two allies jointly made an official announcement earlier in the day to deploy the US missile defense system in the US Forces Korea (USFK), some two years after the USFK commander took issue with the need for the THAAD deployment on the Korean peninsula.

The two allies claimed that the US interceptors will target the Democratic People's Republic of Korea (DPRK)'s nuclear and missile threats alone, not any other third country, but it caused strong backlashes from neighboring countries and deepened worries among politicians about regional tensions.

China's foreign ministry said in a statement Friday that the Chinese side is "strongly dissatisfied with and firmly opposes to" the THAAD deployment in South Korea as the deployment is not conducive to achieving denuclearization on the peninsula and maintaining its peace and stability.

Russia has repeatedly expressed opposition to the deployment, with Alexander Timonin, Russian Ambassador to South Korea, saying in February that the US missile defense system would neither lend any support to peace and stability in Northeast Asia, nor any benefit to resolving nuclear issues on the peninsula.

South Korean politicians said the THAAD deployment will heighten regional tensions, rather than helping resolve the peninsula's nuclear issue. The minor opposition Justice Party said the decision will certainly cause a more dangerous security crisis in the region than the DPRK's missile crisis as it came amid strong oppositions from China and Russia, calling for the withdrawal of the decision.

People's Party, which plays a casting vote between ruling Saenuri Party and main opposition Minju Party, expressed its clear opposition to the THAAD deployment, saying the South Korean government had easefully dealt with China's oppositions. It noted Seoul should have considered more deeply the possible economic effects from the worsening relations with China.

Following the THAAD announcement, shares of South Korean companies which depend heavily on Chinese consumers and travelers for revenue, fell sharply. LG Household & Health Care tumbled 4.5 percent, with leading cosmetics maker Amore Pacific plunging 4.7 percent. Travel agency shares, including Hanatour Service and Modetour Network, also lost ground.

The governing party expressed support for the THAAD deployment, saying it would tackle the DPRK's nuclear and missile threats, including the recent test-launches of Musudan intermediate-range ballistic missiles.

Pyongyang said last month that it had succeeded in test-firing the missile for the first time, threatening US military bases in Guam and Japan as well as in South Korea. The missile, known to be capable of carrying a nuclear warhead, is fired from a mobile launcher, making it hard to detect and track in times of emergency.