Middle finger
There is no need to be a member. The US sits on the security council which referred other non-member countries to the ICC. The fact is requests for investigation were submitted over the deaths of 1 million Iraqis.
Any keen observer can infer that kelele za marekani are designed to set a road map to sabotage the investigation of Israel for atrocities against Palestinians.
Henry Kissinger has never been handed over for war crimes prosecutions. Any time he has been on the verge of being arrested outside the US, he is warned and escapes.