Pyongyang: North Korea on Monday warned it would take "physical action" against South Korea and the US for the Terminal High Altitude Area Defence (THAAD) system which is expected to be deployed in Seoul by the end of 2017. "Our army is ready to attack mercilessly and reduce enemies into a sea of fire if it receives orders right now," the Korean Central News Agency (KCNA) reported in what was Pyongyang's first reaction to the measure announced on Friday. Pyongyang "will undertake physical actions as retaliation against THAAD, an instrument of aggression and US world domination, at the time its specific location is confirmed," warned North Korean military leaders quoted by KCNA. The threats were made after North Korea test-fired a new submarine-based ballistic missile on Saturday, which was seen as a direct response to new US sanctions on North Korean leaders for human rights abuses. According to authorities in Seoul, the launch, which took place in the East Sea near the northeastern city of Sinpo, failed during the flight phase. However, they still considered it an advancement in North Korean missile technology, EFE news reported. The new arms test came after the US imposed direct sanctions on Kim Jong-un and another ten North Korean leaders for the first time last week, which was described by Pyongyang as a "declaration of war". The agreement to deploy the THAAD anti-missile system was signed by Seoul and Washington shortly after Pyongyang conducted its fourth underground nuclear test earlier this year and launched a rocket with intercontinental ballistic missile technology. The THAAD project, a costly system designed to intercept missiles in their terminal phase of flight, has generated strong protests from both North Korea, who considers it as a direct threat to its security, and China as well as Russia.