The original article quoted the marines and experts by name.
I read of lot of other articles, which claimed that this was material the UN had sealed and the marines broke the seal. But each of those articles quoted an anonymous source, NOT even an official source, who "spoke on condition of anonymity". That is supposed to refute the word of the marines and other NAMED experts quoted in the original article, that broke the story?!
http://www.pittsburghlive.com/x/search/s_128200.html The following is a quote from the several later articles, trying to discredit the find.
"What happened apparently was that they broke IAEA seals, which is very unfortunate because those seals are integral to ensuring that nuclear material doesn't get diverted," the expert said, speaking on condition of anonymity.