This is not entirely correct; the US is not a party to the Rome Statute, true, but it in fact Bill Clinton did sign the Rome Statute, but it was never submitted for ratification, and George W. Bush's administration sent a note purporting to retract the signature (as a means of avoid obligations that attach to signatories to treaties even prior to ratification under the Vienna Convention on Treaties, specifically, the obligation not to work to undermine the treaty's purpose.)

The US has engaged more positively (but without any moves toward ratification or even retracting the purported retraction of its signature) with the ICC under the Obama Administration.