What's the world's best defence against nuclear weapons?

Leaders from more than 50 countries, including Prime Minister Justin Trudeau, metin Washington, D.C., for a Nuclear Security Summit meant to keep the most devastating weapons out of the reach of would-be attackers.

• Nuclear terrorism scenario tests world leaders
• Activists want Canada to push for nuclear-free world

U.S. President BarackObama's fourth and final summit wasfocused on efforts to lock down vulnerableatomic materials to prevent nuclear terrorism. North Korea'snuclear defiance was also high on the agenda.

Obama saidtoday thatal-Qaeda has long sought nuclear materials and that the Islamic State in Iraq and Syria group has used chemical weapons. He saidextremists linked to the Paris and Brussels attacks videotaped a senior manager at a Belgian nuclear facility.

Obama saidthere's no doubt that if ISIS "madmen" got a nuclear bomb or material, they would use it to kill as many people as possible. He saidthat would be a disaster that would "change our world."

What's the world's best defence against nuclear weapons?

Readers gave us their thoughts in the latest CBC Forum a live, hosted discussion about topics of national interest.

(Please note that user names are not necessarily thenames of commenters. Some comments have been alteredto correct spelling andto conform to CBC style. Click on the user name to see the comment in the blog format.)

"Nuclear bombs are pure evil. Absolutely no one, no country on this planet, should be allowed to have them, make them, store them or use them. They should be completely banned worldwide." The OpenNiqabi

"The best way would be to phase out nuclear power. It is the commercial trade in nuclear expertise and materials thatlegitimizesits spread all over the world. Without nuclear power it would be clear that trade in nuclear materials is only for weapons purposes far easier to regulate and police. Look at what we just had to go through with Iran." Kai in To

"In this modern communication and computer database age, there is absolutely no reason whyany country holding [weapons or raw materials]cannot account for their holdings and any discrepancy in such stocks.Yes, thereis a cost in doing so, but I suggest it is much less thanthe cost of not doing so." novascotiafarmer

"There is nuclear material everywhere now and even the waste products are hazardous and potentially can be weaponized.Perhaps an international force could be established to maintain records and provide security." Kevin in Vancouver

"Mutual deterrence has worked well as a general international policy for the nuclear threat between nations such as China and the U.S. It's the possibility of a dirty bomb in the hands of terrorists that is the worst scenario. Apart from the continued maintenance of strict controls over the raw materials, I see no way to prevent such an attack. After all, we haven't had much luck against suicide bombers wearing explosive vests, and the dirty bomb wouldn't even require a suicide attack." bluenose

"There will be no banning of such weapons; there is no trust. So, unhappily, we have to learn to live with these weapons.Mutually assured destruction is still the way to go." Stu Peters

You can read the complete discussion below.

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