In other words, it's hacking. Cyber-espionage is a form of cyber-attack. It's an offensive action. It violates the sovereignty of another country, and we're doing it with far too little consideration of its diplomatic and geopolitical costs.

The abbreviation-happy U.S. military has two related terms for what it does in cyberspace. CNE stands for "computer network exfiltration." That's spying. CNA stands for "computer network attack." That includes actions designed to destroy or otherwise incapacitate enemy networks. That's—among other things—sabotage.

CNE and CNA are not solely in the purview of the U.S.; everyone does it. We know that other countries are building their offensive cyberwar capabilities. We have discovered sophisticated surveillance networks from other countries with names like GhostNet, Red October, The Mask. We don't know who was behind them—these networks are very difficult to trace back to their source—but we suspect China, Russia, and Spain, respectively. We recently learned of a hacking tool called RCS that's used by 21 governments: Azerbaijan, Colombia, Egypt, Ethiopia, Hungary, Italy, Kazakhstan, Korea, Malaysia, Mexico, Morocco, Nigeria, Oman, Panama, Poland, Saudi Arabia, Sudan, Thailand, Turkey, UAE, and Uzbekistan.

When the Chinese company Huawei tried to sell networking equipment to the U.S., the government considered that equipment a "national security threat," rightly fearing that those switches were backdoored to allow the Chinese government both to eavesdrop and attack US networks. Now we know that the NSA is doing the exact same thing to American-made equipment sold in China, as well as to those very same Huawei switches.

The problem is that, from the point of view of the object of an attack, CNE and CNA look the same as each other, except for the end result. Today’s surveillance systems involve breaking into the computers and installing malware, just as cybercriminals do when they want your money. And just like Stuxnet: the U.S./Israeli cyberweapon that disabled the Natanz nuclear facility in Iran in 2010.

This is what Microsoft's General Counsel Brad Smith meant when he said: "Indeed, government snooping potentially now constitutes an 'advanced persistent threat,' alongside sophisticated malware and cyber attacks."

When the Chinese penetrate U.S. computer networks, which they do with alarming regularity, we don't really know what they're doing. Are they modifying our hardware and software to just eavesdrop, or are they leaving "logic bombs" that could be triggered to do real damage at some future time? It can be impossible to tell. As a 2011 EU cybersecurity policy document stated (page 7):

...technically speaking, CNA requires CNE to be effective. In other words, what may be preparations for cyberwarfare can well be cyberespionage initially or simply be disguised as such.

We can't tell the intentions of the Chinese, and they can’t tell ours, either.