This is not the other side collecting military, political, or economic, intelligence on us. This is the other side collecting intelligence on how we collect intelligence. More later.
2015 - Sequence of hacks of health care companies, background investigators, culminating (so far) in OPM. Chinese obtain security clearance background information on millions of Feds.
2015 - State Department and unclassified White House networks penetrated again, probably by Russians.
2014 - State Department and unclassified White House networks penetrated.
2013 - NSA contractor absconds first to China, then to Russia, with an immense trove of documents on NSA foreign sigint and cyber programs, including US programs to monitor Russian Chinese strategic forces, to which the Russians and Chinese gain access,
2015 - State Department and unclassified White House networks penetrated by Russians.
2011 - RQ-170 drone captured by Iran, later shared with China (and perhaps Russia). Not clear how much damage to sensitive on board equipment was caused by the crash-landing
2008 - Russians penetrate SIPRNET. Allegedly no exfiltration of data.
2008 - Army enlisted person provides millions of low-level diplomatic traffic (some of which has sensitive information) to wikileaks.
2006 - State unclassified networks penetrated with huge exfiltration of data
2001 - EP3E crash lands in China, crew fails to destroy intelligence equipment (which the Chinese then dismantle and examine for weeks)