How could the USA’s westward expansion cause an intense debate over slavery?

In the supreme court’s decision in korematsu v. united states, the court said that korematsu

Under the new imperialism europe did not need large numbers of people to control territories because of

Which of these did the soviet union do in 1961? it built a wall through berlin to keep people from moving to the west. it used force to destroy a wall the united states had built in berlin. it convinced the british and french to merge their zones in berlin with the soviet zone. it threatened to bomb berlin if the united states did not leave within 30 days.