The Seljuks were invading
Answer:
The Southern states wanted to count the entire slave population. This would increase their number of members of Congress.
Answer: It causes flooding which washed away fertile top soil.
Explanation:
This policy was called "containment" - the idea was to contain communism from spreading to new countries without trying to actively challenge the communist system in the countries that already had it.
This policy lead to some proxy wars, in which the US fought the Soviet Union for the free countries.