UNITED NATIONS - An assembly of 123 countries gathered at the United Nations agreed to allow the International Criminal Court to prosecute those responsible for the crime of aggression, officials said the other day.

The state-parties to the Rome Treaty, which created the ICC, adopted by consensus on Thursday a resolution “on the activation of the jurisdiction of the court over the crime of aggression,” a court statement read. The move has been under discussion for years, with Britain, France and Japan among countries reluctant to allow their nationals to be tried under such a charge.

Aggression will be added to crimes against humanity, genocide and war crimes, which the ICC is currently tasked with investigating and bringing to justice.

At its founding in 1998, the ICC’s backers could not agree on a legal definition of “aggression,” but a consensus was finally reached at a conference in Kampala in 2010.

The resolution adopted late Thursday, however, does not allow for retroactive prosecutions and only applies to state-parties, which means China, Russia and the United States will not be affected.

The International Peace Institute, a New York-based think thank, said it was doubtful whether aggression will be prosecuted any time soon, given the interpretations of the legal meaning and the political interests involved.

Member-states can declare that they do not accept the jurisdiction of the court over the crime of aggression, complicating the application.