Why did the ICC decide not to probe alleged US atrocities in Afghanistan? The ICC said that investigating these alleged US atrocities would not serve the interest of justice. What do they mean by that and is the ICC fearful of a US retaliation against it?
The US is not a State party to the ICC, and doesn't recognize its legitimacy or authority.
This would not matter if the US generally cooperated with the ICC, but that is not the case: the US recently issued Visa bans on ICC staff.
As such, even if the court were to find something it would be pointless to prosecute because, unable to get their hands on the perpetuators, the court wouldn't be able to offer proper remedy.
The ICC does not investigate every crime in the world, or even every war crime. They act
- when the UNSC refers cases to the court, or
- when individual nations refer cases to the court, or
- when individual states are unwilling to prosecute war crimes.
Since the first two conditions have not been met, the ICC would have come to conclude that US military justice system is unwilling to prosecute war crimes by their servicemen. Consider the Behenna or Bales cases, which came to a guilty verdict.