Kampala, Uganda (CNN) -- One of the attorneys who prosecuted Nazi war criminals at the end of World War II cautioned the United States, Russia and China on Wednesday over their opposition to the final inclusion of "crimes of aggression" in the mandate for the International Criminal Court.
"Crimes of aggression" were initially included in the court's Rome Statute of 1998, but unlike the other three crimes put under the tribunal's jurisdiction -- genocide, crimes against humanity and war crimes -- crimes of aggression were not defined and jurisdictional conditions were not set.
A review conference, which began May 31 in Kampala and continues through Friday, hopes to accept a proposal that will finally give the court what it needs to try cases of crimes against aggression. But the United States, Russia and China have balked.
"A country should not commit crimes for its own benefit thinking no one will question it," said Benjamin Ferencz, a former chief prosecutor during the 1946 Nuremberg Tribunal that brought top Nazi war officials to justice.
"This is the time all nations in the world should come in full support of the crime of aggression to be part of crimes tried by ICC so that we put to past impunity and open a new chapter to accountability," he said.
As for those opposed, Ferencz said, "the court of opinion will judge them harshly."
Ferencz, 91, accused "the big nations" of delaying inclusion of crimes of aggressions in 1998 "because they felt they would dodge it, make it die out completely."
"They set up conditions that they felt would never be met," he added. "They wanted the crime of aggression defined and wanted to be sure that the U.N. Security Council will run the show when the ICC was implementing it."
The proposal under consideration in Kampala defines crimes of aggression as "the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State, of an act of aggression." The trigger for the action is that it violates the U.N. Charters.
But three proposals are under consideration regarding when and how an investigation might proceed. Two proposals require the U.N. Security Council to determine whether an act of aggression has been committed, but one of those allows an investigation to proceed without the Security Council determination for six months.
The third proposal would give the authority to trigger an investigation to the tribunal's pre-trial Chamber, the U.N. General Assembly or the International Court of Justice.
The five permanent members of the U.N. Security Council -- China, Russia and the United States along with France and the United Kingdom -- have veto power on the 15-member council.
The 33 African states that form the biggest single continental block among the 111 states who have signed onto the Rome Statute last week issued a joint statement in Kampala opposing the suggestion to make the U.N. Security Council the arbiter of crimes of aggression.
Individual countries and the Security Council may refer cases from the other three crimes under the court's jurisdiction to the prosecutor, or, under certain circumstances, the prosecutor may begin an investigation unsolicited.
"The trick behind all this is that the big countries are still in the cold war," Ferencz said. "No big nation trusts the other on how it will be handled in case it becomes party to the Rome Statute and when is fully implemented."
Ferencz's comments came just a day after lawyers representing Sudanese President Omar al-Bashir accused ICC chief prosecutor Luis Moreno-Ocampo of politicizing the court's operations by focusing on Africa. Al-Bashir was indicted in March on three counts of genocide, five of crimes against humanity and two of murder, most connected with the Darfur region of Sudan.
Al-Bashir's attorneys urged Moreno-Ocampo to indict former U.S .President George W. Bush and his close ally former British Prime Minister Tony Blair for lying to the world of existence of weapons of mass destruction to support their invasion of Iraq in 2002.
U.S. State Department legal adviser Harold H. Koh, attending the Kampala conference, urged attendees to deliberate slowly.
"Surely finishing the unfinished business of Rome does not mean rushing to a premature conclusion of institution- transforming amendments on which there is not yet genuine consensus," Koh told the conference.
"Instead, finishing the work of Rome means building a stronger court with a renewed commitment to pursuing meaningful solutions by genuine consensus that can advance the cause of human rights and international justice," he said.
Koh argued against finalizing the Rome Statute's sections on crimes of aggression, saying not enough agreement yet existed to move forward.
"Although we respect the considerable effort that has gone into (drafting the amendment), we believe that without agreed-upon understandings, the current draft definition remains flawed," he said.
Among the items that lacked "agreed-upon understandings," he said, were the meaning of the definition of crimes of aggression and the concern about potential prosecutions of "mere acts of aggression, as opposed to the 'wars of aggression' that were prosecuted in Nuremberg and Tokyo."
China is not a party to the Rome Statute. The United States and Russia signed the document but have not ratified it, and the U.S. Congress in 2002 nullified the U.S. signature on the document. Israel and Sudan also "unsigned" the statute. Congress also passed an act that year preventing U.S. service members from providing military aid to countries that had ratified the Rome Statute and giving the president permission to authorize military force to free any U.S. soldier, sailor, airman or marine who is being held by the International Criminal Court.
That same year, the United States threatened blanket vetos of the renewal of the U.N. peacekeeping mission unless the ICC granted its troops immunity from prosecution. As a compromise, the Security Council passed a resolution granting immunity for a year to U.N. nations who were not parties to the court and renewed that resolution in 2003.
But the council dropped the exemption in 2004 when photographs of U.S. troops abusing Iraqi prisoners at Abu Ghraib surfaced.
Ferencz, who served in the U.S. Army during World War II, said such maneuverings might delay but would not stop prosecutions.
"The world is changing very fast and perpetrators of atrocities will be held to account even after a century," he warned.
"No one should use his military prowess to terrorize the rest of the world thinking no one will hold him accountable."
But the former prosecutor was optimistic that the holdouts would see reason.
"I hope that President Obama, after accepting the Nobel Peace Prize, will also support the ICC on crimes of aggression and that Russia and China will not find it acceptable to commit the old mistakes to stop the process," he said.