China and Russia protest South Korea's Terminal High Altitude Area Defence system, which they say could destabilise the regional balance of power.
US and South Korea announced on Friday they would deploy an advanced missile defence system in South Korea to counter a threat from North Korea, drawing sharp criticism and reactions from China and Russia over "regional stability."
The Terminal High Altitude Area Defence, or THAAD, anti-missile system will be used only as protection against North Korea's growing nuclear and ballistic missile capabilities, the South Korean Defence Ministry and the US Defence Department said in a joint statement.
"This is an important ... decision," General Vincent Brooks, commander of US forces in South Korea, said in a statement. "North Korea's continued development of ballistic missiles and weapons of mass destruction require the alliance to take this prudent, protective measure to bolster our ... missile defence."
Tipping the scales
The governments of China and Russia worry this plan might tip the balance of power in the Pacific in favour of the United States.
Chinese Foreign Ministry spokesman Hong Li said the country lodged protests with the American and South Korean ambassadors.
China believes the system to be deployed would "seriously damage the strategic security interests of countries in the region."
Beijing said on Friday the system would destabilise the security balance in the region without achieving anything to end the North's nuclear programme. China is North Korea's main ally but opposes its pursuit of nuclear weapons and backed the latest United Nations sanctions against Pyongyang in March.
"China strongly urges the United States and South Korea to stop the deployment process of the THAAD anti-missile system, not take any steps to complicate the regional situation and do nothing to harm China's strategic security interests," the foreign ministry said in a statement.
Russia strongly reacted to the THAAD announcement, saying it would have "irreparable consequences."
"The United States, supported by its partners, is continuing to build up the potential of the Asia-Pacific segment of the global anti-missile defence system, which undermines the established strategic balance in the (region) and beyond," the foreign ministry said in a statement.
Russia's statement said these actions "most negatively affect global strategic stability."
The decision of US and South Korea to deploy the missile defence system became known to the public on Friday as the US Department of Defence published a press release on its official website.
There is no further information on who will control the system.
According to the US statement, the THAAD system will be able to detect North Korean missiles and destroy them.
The system has the ability to detect the launch of ballistic missiles and launch an interceptor missile which will destroy the enemy's projectile in the terminal phase of its flight.
Discussions between US and South Korea began in February after North Korea fired a long range missile.
The announcement came on the heels of US imposed sanctions on North Korean leader Kim Jong-un over committing human right abuses.