Instead, the South Korean side says its working on creating its own missile defense perimeter.
相反地,韩国方面表示正在建造自己的导弹防御周界。
英语百科
All round defence
All-around defense and perimeter defense are synonyms for one category of the (relative) positioning of defensive fighting positions that are supposed to give military units and sub-units the ability "to repel an attack from any direction by being organized or sited for all round defence". This defense can be used by military units from squad up.