Why did united state get involved when north korea invaded south korea

Why did president lincoln place general mclellan under the command of general halleck? a. mcclellan failed to capture richmond. b. mcclellan was responsible for the north's defeat at the second battle of bull run. c. mcclellan failed to defeat lee at antietam creek.

Western sahara is occupied by whom? a. mauritania b.algeria c. morocco d. tunisia

From 1990 to 2008, by what percent did the world’s most developed economies cut their greenhouse gas emissions?