In what ways did the people protest against the war ?

Many Americans opposed the war on moral grounds, appalled by the devastation and violence of the war. Others claimed the conflict was a war against Vietnamese independence, or an intervention in a foreign civil war; others opposed it because they felt it lacked clear objectives and appeared to be unwinnable.

i believe it was spain

the monroe doctrine is the best known u.s. policy toward the western hemisphere. buried in a routine annual message delivered to congress by president james monroe in december 1823, the doctrine warns european nations that the united states would not tolerate further colonization or puppet monarchs.