How do we know?? With past weapons bans - like cluster munitions, landmines - countries outside the treaties shifted their behaviour after they entered into force. Learn more: https://www.icanw.org/entry_into_force_briefing_paper

The treaty will also impact the money going to nuclear weapons. Banks, insurers and pension funds will divest from companies that produce nuclear weapons, and lead these companies to stop producing nuclear weapons. It’s already happening

Another key obligation is that states parties are legally bound to urge try to get more states to join the treaty. So in bilateral meetings, at state visits, at the @unitednations, they will push nuclear-armed states and nuclear endorsing states to join the #nuclearban too.

Starting 22 jan, all countries that have ratified the treaty must comply with its prohibitions and positive obligations, like assisting victims of nuclear use and testing. This is key: the #nuclearban treaty will help impacted communities! https://www.theguardian.com/world/2020/oct/25/now-that-nuclear-weapons-are-the-pacific-demands-truth-on-decades-of-testing