Who is Viktor Bout, the arms dealer who could be swapped for Griner?

Bout was almost certainly a GRU agent, or at least a GRU asset," said Mark Galeotti, an expert on the Russian security services at the Royal United Services Institute think-tank, referring to Russia's military intelligence service. “His case has become totemic for the Russian intelligence services, who are keen to show that they don’t abandon their own people,” Galeotti added.