WASHINGTON — The United States and South Korea have decided together to deploy the US Army's Terminal High Altitude Area Defense System (THAAD) to the Korean Peninsula as North Korea continues to conduct intermediate-range ballistic missile launches.

According to a Pentagon statement released Thursday night, the US and South Korea will deploy THAAD "as a defensive measure to ensure the security of the ROK and its people and to protect alliance military forces from North Korea's weapons of mass destruction and ballistic missile threats."

ROK is an abbreviation for Republic of Korea often used by the US military for South Korea.

The US and South Korea have been conducting formal discussions regarding the "feasibility" of sending a THAAD battery since early February, according to the Pentagon. The battery will be operated by US Forces Korea, the statement indicated.

A joint US-South Korea working group reviewed THAAD's military effectiveness in Korea and "is in the final stage of preparing its recommendation" for South Korea's minister of national defense and US Defense Secretary Ash Carter on the "optimal site" in the country for "the system's effectiveness and for environmental, health, and safety requirements," the statement read.

The Pentagon took pains to stress that the THAAD system deployed to Korea will be "focused solely on North Korean nuclear and missile threats" and not directed at any other nations.

One of the reasons the decision to deploy THAAD took time was China's opposition to a THAAD deployment to South Korea. "This is a very sensitive issue for the partners throughout the region," Lt. Gen. David Mann, the commanding general of Army Space and Missile Defense Command, told reporters in March, "especially when you look at South Korea, one of the largest trading partners, China, in the region, and so we don't minimize the sensitivity of these discussions."

The Pentagon said South Korea and the US are "working closely to ensure the swift deployment of THAAD" to the peninsula.

Each THAAD unit consists of six truck-mounted launchers, 49 interceptors, a fire control and communications unit, and an AN/TPY-2 radar.

The first THAAD battery — and currently the only deployed system — was set up expediently in Guam several years ago to protect US forces and allies in response to North Korean aggression. That battery appears to be there for the long haul.

And North Korea's recent missile testing has grown more complex and more concerning. North Korea has recently launched a payload into orbit and appears to be preparing for another test of its Musudan medium-range missile.

According to reports last month, official sources said that North Korea appears to have deployed a Musudan missile — with ranges that cover all of South Korea and Japan but could reach as far as Guam — near its east coast.

The Army will have five operational THAAD units by the end of the year as demand signals for capability growth across multiple regions. The Army still has a requirement for nine batteries but has only funded seven in the five-year defense plan.

Earlier this year Carter said THAAD's arrival on the Korean Peninsula was going to happen, calling it "a necessary thing."

Twitter: @JenJudson