British Prime Minister David Cameron, in a press conference with President Obama. (Chip Somodevilla/Getty Images)

The cultural norms against waging war in cyberspace are slowly eroding.

On Sunday, the UK government announced it that it's actively building an offensive cyber capability, making it the first government to openly admit doing so. Britain will have "hundreds" of hackers at its disposal, defending the country's digital infrastructure, but also developing the power to deter and to strike.

The act of putting together a cyberarmy is hardly worth mentioning; Britain's national security strategy documents from 2010 telegraph that pretty well. Besides — if you're a world leader and you're not investing in online defenses, you're doing it wrong.

Here's what Britain likely won't be doing: launching Stuxnet-style, standalone attacks. Instead, Philip Hammond, the country's defense secretary, envisions the cyber capability supplementing conventional arms by disabling enemy ships and weapons. That's not much different from the way that U.S. forces have thought about deploying their cyber capabilities. In short, Britain's activities in cyberspace aren't about to become a milestone along the road to all-out cyberwar.

But the admission from Hammond is a sign that the international community's wariness of cyberwarfare may be crumbling, and that may be just as important. Governments have mostly been gun-shy when it comes to launching attacks through cyberspace; fears that a strike could reveal a state's capabilities, or could be traced back to the wrong source, mean that countries tend toward caution. That might no longer be the case if other countries, taking Britain's lead, also announce their offensive capabilities as a deterrent measure.

"Such aggressive statements can be counter-productive," Thomas Rid, a scholar in war studies at King College London, told the Financial Times. "Other actors will want to react in kind, making everybody less secure.”

Over the short term, that could create an environment where online clashes become more likely. But in the long run, Britain's decision to go public might also be seen as the first step in the development of an international legal regime that publicly addresses how countries should behave militarily in cyberspace.