North Korea's military said on Monday it will make a "physical response" to moves by the United States and South Korea to deploy the advanced THAAD missile defense system on the Korean peninsula.
The United States and South Korea said on Friday that the Terminal High Altitude Area Defense (THAAD) anti-missile system will be used to counter North Korea's growing nuclear and ballistic missile capabilities.
The announcement was the latest move by the allies against the North, which conducted its fourth nuclear test this year and launched a long-range rocket, resulting in tough new U.N. sanctions.
"There will be physical response measures from us as soon as the location and time that the invasionary tool for U.S. world supremacy, THAAD, will be brought into South Korea are confirmed," the North's military said in a statement.
"It is the unwavering will of our army to deal a ruthless retaliatory strike and turn [the South] into a sea of fire and a pile of ashes the moment we have an order to carry it out," the statement carried by the official KCNA news agency said.
The North frequently threatens to attack the South and U.S. interests in Asia and the Pacific.
South Korea's Defence Ministry spokesman Moon Sang-gyun warned the North not to take "rash and foolish action." Otherwise, he said, it would face "decisive and strong punishment from our military."
The move to deploy the THAAD system, which drew a swift and sharp protest from China, came a day after the U.S. Treasury Department blacklisted leader North Korean leader Kim Jong Un for human rights abuses.
North Korea called the blacklisting "a declaration of war" and vowed a tough response.
South Korean President Park Geun-hye said on Monday the THAAD system was not intended to target any third country but was purely aimed at countering the threat from the North, in an apparent message to Beijing.
"I'm certain the international community knows full well that we have no intention whatsoever to target any other country or threaten them," Park said at a meeting with her senior advisers, according to the Blue House.
Chinese Foreign Minister Wang Yi said on Saturday that THAAD exceeded the security needs of the Korean peninsula, and suggested there was a "conspiracy behind this move."
South Korean Finance Minister Yoo Il-ho downplayed the possibility that China, Seoul's biggest trading partner, would retaliate economically over the THAAD decision.
"[China] is expected to separate politics and economics," he told lawmakers on Monday in response to a question during a parliamentary session.
A South Korean Defence Ministry official said selection of a site for THAAD could come "within weeks," and the allies were working to have it operational by the end of 2017.
It will be used by U.S. Forces Korea "to protect alliance military forces," the South and the United States said on Friday. The United States maintains 28,500 troops in South Korea, a legacy of the 1950-53 Korean war.
The system will be focused solely on North Korean nuclear and missile threats and would not be directed towards any other nation, the two countries said last week.