“‘The U.S. can get pretty far,’ says Matt Devost, managing director at Accenture Security. ‘I would say in a majority of significant attacks, the U.S. government has a high level of confidence with regards to who was involved.
‘But, it might not have the political will to release those details or the methods in how the attribution was achieved,’ he says.”
Source: Cyber Wars: How the U.S. Stacks Up Against its Digital Adversaries | US News