The number of countries possessing the makings for a nuclear weapon has dropped by almost one-quarter during the past two years, according to a study by the U.S. based Nuclear Threat Initiative.
But the study released Wednesday says there are "dangerous weak links" in nuclear materials security that could be exploited by terrorist groups.
The Nuclear Threat Initiative says Mexico, Sweden, Ukraine, Vietnam, Austria, the Czech Republic and Hungary have removed all or most of the weapons-usable nuclear materials from their territory since 2012. It says there are 25 countries with at least one kilogram of weapons-usable nuclear materials, down from 32 countries in 2012.
Among nuclear capable countries, the study ranked Australia as having the best nuclear security arrangements, followed by Canada, Switzerland, Germany and Norway. The United States was ranked number 11. The report says the weakest nuclear security is in Israel, Pakistan, India, Iran and North Korea.
The study assessed accounting methods, physical security and transportation security.
The report says about 1,400 tons of highly enriched uranium and 500 tons of plutonium are stored in hundreds of sites around the world.
The Nuclear Threat Initiative said a significant portion of the material is poorly secured and vulnerable to theft or sale on the black market.