The 32 nations with materials that can fuel atom bombs are typically mum on security, which looks to the public like a closed world of barbed wire and armed guards. Behind the scenes, atomic insiders have long told horror stories of risky practices and security flaws that might let the crucial ingredients for nuclear weapons fall into the wrong hands.

Now, for the first time publicly, experts have surveyed the precautions each country has in place and ranked the nations from best to worst. The study is full of surprises and potential embarrassments: for instance, Australia takes first place in nuclear security and Japan comes in at No. 23, behind nations like Kazakhstan and South Africa.

The United States? It ties for 13th place with Belgium. Last place goes to North Korea, a police state that the report finds to be seriously deficient on issues of atomic security, and next-to-last to Pakistan.

The edgy ranking is a joint endeavor of the Nuclear Threat Initiative, a private advocacy group in Washington, and the Economist Intelligence Unit, a company in London that does risk analyses. Their goals are to stir debate on how to promote security and to encourage governments to strengthen protections against atomic terrorism.