Yes, one does.
> The Kuala Lampur War Crimes Commission tried and convicted George W. Bush and Tony Blair for "crimes against peace" in 2011 under the principle of universal jurisdiction.
Ignoring the question of the legitimacy of the KLWCC (as others have addressed that issue effectively), the principle of universal jurisdiction is a basis under which to assert jurisdiction, so its use is an acknowledgement of the need to establish jurisdiction, rather than support for the claim that jurisdiction is unnecessary for such a trial.