Who is Viktor Bout, the Russian arms dealer and 'Merchant of Death' swapped for Brittney Griner?

Former U.S. Drug Enforcement Administration officials who were involved in the effort to bring "Merchant of Death" Viktor Bout to justice have characterized his trade to Russia for WNBA star Brittney Griner's freedom as a "disgrace" and a "grave threat" to U.S national security. Derek Maltz, the DEA special agent in charge who oversaw the investigation of Viktor Bout, said its, "not a fair swap." Maltz added, "We left a Marine behind, sitting in jail, who fought for their country, this is a joke." Maltz is referring to Paul Whelan, a former U.S. Marine who was arrested in Russia in 2018. He was accused of spying and sentenced to 16-years in prison.