Another mysterious explosion in Iran this week, the third in a month, has stirred speculation that a mysterious hand was once again striking at Iran's nuclear programme.
The blast on Sunday occurred at a steel plant in the city of Yazd, killing seven people and seriously wounding 12 others. A number of the victims were foreigners, according to Iranian officials.
Citing Western intelligence sources, the German newspaper Die Welt reported last month that North Korea has been providing Iran and Syria with maraging steel - a type suitable, among other things, for use in gas centrifuges employed in uranium enrichment. Its strength and malleability also makes it useful in construction of exhaust systems for missile engines.
The United States and other countries monitor the import and export of maraging steel because of its possible use in centrifuges. Iran has not identified the type of steel being manufactured at the plant.
The blast was initially attributed by officials to water accidentally coming into contact with heated implements. Later, however, a local member of Parliament, Ali Akbar Oliaw, said the explosion had been touched off by defective ammunition that had been included in the scrap metal brought to the privately owned plant.