There are many details left out that could reasonably pin the attacks on the Chinese. While communication back to the source may be obfuscated and hard to pin o

There are many details left out that could reasonably pin the attacks on the Chinese. While communication back to the source may be obfuscated and hard to pin on any particular actors the exploits, shellcode, and malware they use can possibly be tied to other breaches. Like regular programmers, hackers tend to reuse modules, code blocks, techniques, etc. from attack to attack. So whereas the NOAA breach may not conclusively point to China something found during the incident response and forensics phases may connect it to the USPS breach, Lockheed Martin breach, or others. A good example of this technique would be how researchers were able to tie Stuxnet, Flame, DuQu, and Guass to the same actors (probably the US and Israel).