The Prime Minister heads for Korea this morning, for a Nuclear Security Summit hosted by Barack Obama.
John Key will also meet other international leaders on the trip, including the heads of South Korea and the Netherlands.
Mr Obama established the summit two years ago, as a element of his aim of eradicating nuclear weapons.
Mr Key it's making good progress, and holding it on the Korean Peninsula is important because it's easy to see the potential for a catastrophe.
The summit is attended by representatives of more than 50 countries.