I named North Korea as a prime suspect.
So what do you know?
North Korea is helping Iran to prepare an underground nuclear test similar to the one Pyongyang carried out last year.
Under the terms of a new understanding between the two countries, the North Koreans have agreed to share all the data and information they received from their successful test last October with Teheran's nuclear scientists.
The Iranians are busy, too:
"The Iranians are working closely with the North Koreans to study the results of last year's North Korean nuclear bomb test," said the European defence official.
"We have identified increased activity at all of Iran's nuclear facilities since the turn of the year," he said.
"All the indications are that the Iranians are working hard to prepare for their own underground nuclear test."
It's almost like they have something planned.
