Dozens of countries, including New Zealand, have signed a treaty to ban nuclear weapons amid tensions over North Korea's nuclear and missile tests.
The US, Britain, France and others, including Australia, boycotted the event at the annual United Nations gathering of world leaders.
The treaty on the prohibition of nuclear weapons will enter into force 90 days after 50 countries have ratified it. Only a few states were due to deposit their ratification on Wednesday.
No nuclear states are signing - but the treaty effectively criminalises them in international law and declares them to be outlaw regimes, providing a solid basis for international justice if they ever use the things. Assuming there's still people left to care, that is. And while a treaty without the nuclear powers doesn't sound like much of a step forward, its a start towards a safer world.