Communism, at the time, was the main priority of many nations. They didn’t want it to spread.
I am not going to answer in a paragraph of 125 words, but I will give you the answer to the first question; The United States didn't want another country to fall to communism. They officially got involved after the attack of the Gulf of Tonkin (U.S destroyers were stationed there and a radio came in that said they had been fired upon by North Vietnamese forces). (45 words BTW).
The summer monsoon brings a humid climate and torrential rainfall to these areas. Rice and tea are some crops that rely on the summer monsoon. Dairy farms, which help make India the largest milk producer in the world, also depend on the monsoon rains to keep cows healthy and well-fed.
