"In short, everybody has been participating and by working together our nations have made it harder for terrorists to get their hands on nuclear material," Obama said. "We have measurably reduced the risk but…the threat of nuclear terrorism persists and continues to evolve."
Obamas noted that because of the world leaders’ coordinated efforts, terrorist groups have not obtained a nuclear weapon, dirty bomb or radioactive material to launch attacks.
"There is no doubt that if these madmen ever got their hands on a nuclear bomb or nuclear material they would most certainly would use to kill as many innocent people as possible, that’s why our work here remains so critical," Obama added.
The fourth Nuclear Security Summit started on Thursday and will wrap up today. Obama noted that as many as 102 countries have ratified the Convention on the Physical Protection of Nuclear Material, which he expects will come into effect in the coming weeks.