N. Korea Threatens Nuclear Strike, US, S. Korea Begin Drills

Preemptive –adj. done to prevent an unwanted act by another group, country, or force

Drill –n. an exercise done to practice military skills or activities

Vessel –n. a ship or large boat

Sovereignty –n. a country’s independent authority and the right to govern itself

Potential –n. capable of becoming real

Retaliation –n. to take action against someone, group or country to answer to some kind of attack