Nuclear security

World ports 'detect only fraction' of nuclear material

In 2009, US President Barack Obama described the possibility of nuclear weapons falling into the hands of "terrorists" as the most immediate and extreme threat to global security.

Since then, the US has been leading global efforts to secure, consolidate and dispose of nuclear material, culminating in this week's United Nations Nuclear Security Summit in Washington.

Diplomacy has been a large part of these efforts, but they have also been accompanied by efforts to increase surveillance and monitoring at the world's ports, including the port of Rotterdam, Europe's largest.

More than 440 million tonnes of cargo pass through Rotterdam each year, making it a frontline in the effort to stop the transportation of potentially dangerous nuclear materials.

"These are sources coming from all over the world," Rene de Goede, from Dutch Customs, told Al Jazeera.