It has been primarily "Southwest Asia," that the United States has been militarily involved in the 1990s and into the early decades of the new millennium, since this qualifies as the "Middle East," where the US continues to fight terrorism.
C) the bombing of pearl harbor
E) the sinking of the lusitanaia, which carried over 100 American citizens
Here is the excerpt from A Rumor of War which best illustrates Vietnam's uncomfortable climate:
<span><em>The tedium was occasionally relieved by a large-scale search-and-destroy operation, but the exhilaration of riding the lead helicopter into a landing zone was usually followed by more of the same hot walking, with the mud sucking at our boots and the sun thudding against our helmets while an invisible enemy shot at us from distant tree lines.</em></span>
Answer = constitutional monarchy.
Hope this helps!