I'm struggling to understand what the point of these bounties even is. What does this even acomplish? This action looks more petty than results oriented.
1. Drive up the costs for the US to stay in Afghanistan and damage US prestige by making it look like we're losing yet another war to low-tech peasants/farmers.
2. Payback for the US supplying Afghans with arms against the Soviets in the 80s.
In addition to that, to demonstrate power. That Putin can de facto do whatever he wants without paying price since there is inept president in the White House who may be in Putin's bag for one reason or another. I'm not sure the is some "master strategy" behind it. Putin is overrated as a strategist, but he's not nearly as inept as Trump.