Nuclear security

The US dropped 67 nuclear bombs on this tiny island nation — and now it's far more radioactive than we thought

More than 60 years after the US dropped dozens of nuclear bombs on the Marshall Islands, residents of the tiny nation still may not be able to return.

Radiation levels in some areas of the country are almost double what is deemed safe for human habitation, according to a new Columbia University study in the journal Proceedings of the National Academy of Sciences.

Between 1946 and 1958, the United States tested 67 nuclear weapons on the Marshall Islands, a chain of atolls in the Pacific Ocean with a population of just 52,000.

The most famous test, the "Bravo shot," was dropped on Bikini Atoll in 1954 and was 1,000 times more powerful than the bomb dropped on Hiroshima.

Residents of the atoll were displaced, and today it remains uninhabited.