South Korea's President Park Guen Hye defended plans to deploy a US missile defence system in the country on Monday, despite criticism from China and Russia.
The installation of Terminal High Altitude Area Defence (THAAD) system is a "self-defence measure," Park said in a televised speech on the National Liberation Day of Korea, a holiday which celebrates Korea's liberation from Japanese colonial rule in 1945.
This should protect the country from "North Korea's reckless provocations," she continued.
Both China and Russia are opposed to the THAAD system and accuse Washington and Seoul of threatening their security.
In the same speech, Park urged Pyongyang to immediately abandon its controversial nuclear programme. Park reiterated earlier promises to support neighbouring North Korea economically if it stopped developing nuclear weapons.
In July, South Korea and the US announced the deployment of the advanced missile defence system for 2017 in South Korea's Seongju. Seongju is approximately 300 kilometres south of Seoul.
The THAAD system is designed to shoot down a ballistic missile at heights of 40 to 150 kilometres.
North Korea threatened to respond with "physical counteraction," South Korea's Yonhap news agency reported.
In recent months, North Korea has fired several mid-range missiles, including a ballistic missile that landed in the sea off the Japanese coast.
The incident sparked outrage in Tokyo and Washington.
Residents in Seongju have also protested against THAAD, citing health concerns over the electromagnetic waves the system generates. The South Korean government has promised an audit.
The US has already deployed Patriot missiles in South Korea to bolster security against North Korea.