The negotiations will undergo several phases before a conclusion, including an environmental impact review, the spokesman said, adding that the timing of the final conclusion will depend on how smoothly they are processed.

Cho said the allies are planning to complete the deployment of the Terminal High Altitude Area Defense system by the end of this year as previously pledged.

They first announced the deployment plan in February last year following North Korea's long-range missile launch.

On Tuesday, the defense ministry signed a deal with Lotte Group to use the retail giant's golf course in the southern rural county of Seongju for the deployment of THAAD.

The latest development prompted China to ratchet up its threat of retaliatory actions. China claims THAAD, which comes with an advanced radar system, could be used to monitor China's missile positions and undermine its security interests.

Earlier this week, China's foreign ministry spokesman Geng Shuang said the country will take "necessary measures" to safeguard its security interests and that the US and South Korea will have to bear all the consequences.

Lotte Group has recently been a key target of a series of retaliatory measures on South Korean goods and the entertainment industry following the deployment decision.

"(The government) is concerned about some arguments in Chinese (media) that call for a disadvantage on Korean companies," Cho also said in the same briefing. 

"It is desirable that any remarks or behaviors that are not helpful for the development of bilateral relations be restrained," he noted.

The spokesman also said South Korea is currently devising a variety of measures to guarantee the fair treatment of Korean companies operating in China.

"South Korea and China have many challenges between them. The challenges are very massive in fact," the spokesman said.

"Nonetheless, our government is mustering all-out efforts to manage the bilateral relations in a stable manner."

The spokesman again stressed that the THAAD installation is within South Korea's sovereign and autonomous rights to protect its own people from North Korea's nuclear and missile threats. (Yonhap)