Vintage US Military Security Instructions and Rules for Engagement. For Sale

A vintage US Military Field Card with Security Instructions, Rules for Engagement, and Laws of War. This original booklet is 4 inches by 5 inches in size so that soldiers can easily carry it when in the field of combat. Included in the field pamphlet are the Three Interrelated Legal Principles that Apply to All Operations: (a) Military Necessity (b) Proportionality (c) Avoidance of Unnecessary Suffering. I am not sure how I would up with this card, or what year or era it is from. I was in the USAF from 1980-1984 and could have received it then, but I really don’t know. I also don’t know why there are important English to Spanish words and phrases. Maybe someone with more knowledge of US Militaria would know the answers.
This US Military Field Card has great significance, both historical and current, as there seems to be great interest over what the rules for US Military engagement should be. I am just selling the item. As a unique piece of military memorabilia, this booklet would make a nice addition to any collection of military-related materials.