South Korea Concerned Over North’s Submarine Missile Launch

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detect – v. to discover or notice the presence of something or someone; to find

ballistic missile – n. a weapon that is able to travel a long distance and then strike a target; a long-range missile

advanced – adj. beyond the basic level; far along in the course of progress

exploratory – adj. done or created to find something or to learn more about something

preconditions – n. something that must exist or happen before something else can exist or happen