Why did the United States enter into World War I?

Why was mao zedong’s communist china ready to use military tactics against the troops of us general douglas macarthur in korea? a. mao zedong had long planned to declare war against the united states. b. us troops kept marching farther into north korea, getting closer to the chinese border. c. us president harry truman threatened to use nuclear weapons against china. d. kim il sung had requested china’s to declare war against the united states.

Name 3 significant impacts of the tet offensive on the outcome of the war, it's participants, or the public image of the war.

How can you see the impact of ww1 today?