evidence: The vast majority of fentanyl seized is brought into the United States by American citizens at the southern border, according to the U.S. Department of Homeland Security. McCormick and other Republicans compare fentanyl deaths to combat losses in the Vietnam War: Roughly 110,000 drug overdose deaths each of the last two years in which fentanyl was the primary culprit two-thirds of the time, compared to 58,000 reported U.S. casualties in the war. [...] The question, then, may be whether the flow of fentanyl into the United States warrants military action, Corn said.