Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. There were 18 Puerto Ricans Missing in Action in the Vietnam War, from a total of 2,338 people that were listed as Missing in Action. This total, with the exception of PFC. Jose Ramon Sanchez, does not include people of Puerto Rican descent born in the mainland of the United States.Puerto Rico was officially ceded to the United States from Spain under the terms of the 1898 Treaty of Paris which concluded the Spanish-American War. It is a United States territory and upon the outbreak of World War I, the U.S. Congress approved the Jones-Shafroth Act.