Anonymous government sources, especially in cyber security, have a track record of persistent lying
Remember the China chip hacking story by Bloomberg built on anonymous government sources. The alleged fake news was never retracted - even though it was technically not a possible attack if you know how chips are made. (There are chips that had arguably deliberately installed flaws - the Intel chip with the OTP generator that was trivially crackable and the RSA keyfob with the default NSA backdoor).
https://www.bloomberg.com/news/features/2018-10-04/the-big-h...
https://siliconangle.com/2018/10/22/apple-amazon-super-micro...
Relevant: U.S. Had Cyberattack Plan if Iran Nuclear Dispute Led to Conflict (2016) [https://www.nytimes.com/2016/02/17/world/middleeast/us-had-c...]
"Nitro Zeus was part of an effort to assure President Obama that he had alternatives, short of a full-scale war, if Iran lashed out at the United States or its allies in the region."
Tens of millions of dollars, thousands of people... That's not secrecy, just plausible deniability.