The United States has offered a prisoner swap deal to Russia, in order to free WNBA star Brittney Griner and a former US Marine Paul Whelam. The US claims that both Griner and Whelam have been wrongfully detained in Russia. While there is no official confirmation on what is being offered in return, news agency reports citing sources familiar with the matter claim that the US is ready to trade Russian arms dealer Viktor Bout, known as the…