I have seen serious informed speculation that this was developed by Israel to target Iran's nuclear program.
"It was found to target the control systems, made by the German company Siemens, to manage power planets, water supplies, oil rigs and other industrial systems. It used an unprecedented number of zero day exploits (undiscovered flaws in Microsoft software). No piece of malware has ever used four such vulnerabilities at the same time, two was the previous record. The Stuxnet worm is the most sophisticated cyber weapon uncovered to date in the murky world of IT security."
Considering that it is a German manufacturer. Maybe it is possibly someone wanting to lay the blame on Israel for further Anti-Semitic rage to be built. There are many people in this world that do not think that Israel has the right to protect itself, since they don't recognize Israel's sovereignty or right to exist. JMO
