Bruce Schneier writes:
Google made headlines when it went public with the fact that Chinese hackers had penetrated some of its services, such as Gmail, in a politically motivated attempt at intelligence gathering. The news here isn’t that Chinese hackers engage in these activities or that their attempts are technically sophisticated — we knew that already — it’s that the U.S. government inadvertently aided the hackers.
In order to comply with government search warrants on user data, Google created a backdoor access system into Gmail accounts. This feature is what the Chinese hackers exploited to gain access.
Read more on CNN.