One issue was religion disagreements. This divided them and affected the people greatly
The Mexican-American War happened from 1846-1848.
Hope That Helps!
Suprisingly the answer is B. This is the United States primary defense on any missile based attack, even against ICBM's (although not to effective). A perfect example of this type of combat defense is what Israel does, they have actually perfected it.
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Its region because the culture answer is wrong