I have worked in both chip design and security so I feel well qualified to make this assessment: a single mole in the right place who knew what they were doing would definitely be enough. Security holes get past design review all the time by accident. A skilled hacker could easily insert an intentionally obfuscated one that would escape detection.
Yup. And that single well placed mole could have 100 or 1,000 security experts working on their behalf. It is not as though the mole would have to design the hack, only pass necessary documents to a military grade hacking group then implement their modifications.
