The crisis in Ukraine underscores the prescience of the international efforts to eliminate all nuclear weapons and weapon-grade material there after the collapse of the Soviet Union. Their success lowered the danger of deadly nuclear assets falling into the wrong hands.

President Barack Obama and the more than 50 world leaders meeting at the Nuclear Security Summit in The Hague on Monday need to show the same vision. They must seek to eliminate the persistent weak links in the global nuclear security system that can make dangerous materials vulnerable to nuclear terrorists.

There has been progress in securing nuclear materials because of the two previous nuclear summits. Removal of weapons-grade material, for example, has accelerated in 12 countries.  But, unfortunately, the earlier summits focused on what is acceptable by consensus rather than on what is needed to prevent nuclear terrorism.

Terrorist groups are actively seeking nuclear weapons or material. There are more than 100 incidents of theft or misuse of nuclear material each year.  Twenty-five countries now possess weapons-usable nuclear material and nuclear facilities are expanding into dangerous neighborhoods around the globe. Virtually every state has highly radioactive material that could be used in a dirty bomb.

This summit is actually the beginning of the end of the heads-of-state meetings. The Washington–hosted gathering in 2016 will likely be the last. So these two meetings must yield results. Together they can form a solid foundation for an effective governance system for the world’s nuclear materials and facilities, creating a springboard for new policies and action.