The NSA tried to wreck North Korea's nuclear weapons lab using the centrifuge-knackering malware Stuxnet, and ultimately failed, multiple intelligence sources claim.

US spies developed Stuxnet with the Israelis to attack and break Iran's nuke-fuel equipment from the mid to late 2000s. The software nasty was tweaked to thwart North Korea's fuel processing systems, too, we've now heard.

The malware was designed to infect the Siemens AG SCADA control software on the hermit nation's nuclear centrifuges, and the Windows PCs connected to them, Reuters reports today.

It was widely rumored, and later confirmed by whistleblower Edward Snowden, that Stuxnet was developed by a NSA and Israeli collaboration known as Operation Olympic Games. The software, which went through multiple rewrites, wore out the motors in the centrifuges used by Iran to separate uranium, and triggered dangerous overpressure during the manufacturing process.

Intelligence agents now say a similar attempt was made about five years ago to knacker the equipment North Korea was using, by adapting the Stuxnet code to target Korean-language SCADA systems. But the mission failed because no one could be found to smuggle the malware's executables into the highly secret nuclear facility.

In comparison to Iran, North Korea is in a medieval state of internet development. Owning a computer without government permission will earn you and quite possibly generations of your family a life-long stretch in a harsh labor camp. Only the highest echelons of government and the military have access to the open internet. There is simply no need for citizens to own USB sticks, let alone sticks laden with Uncle Sam's malware, under the brutal North Korean regime.

Under such circumstances, it's difficult to see how someone could bring a USB stick containing Stuxnet into a Nork nuclear facility. Access is tightly controlled, and North Korea may also have nuclear facilities that aren't known to the US given the highly closed-off nature of the military state.

The NSA declined to comment on the allegations of an attack on North Korea, and has never commented on the Iranian attacks either. ®