"So we can all hack the US Government back now without worrying about getting extradited?"
you have MY permission, if they're invading your computer without probable cause, and without any kind of legal approval in the UK. They should get a UK warrant first. Then it would be _legal_ in the UK to do that. Or let the UK gummint do it on the US gummint's behalf. Then it's all above-board diplomatically.
But invading your computers? bad idea. hack 'em back. [if you don't mind the legal fees associated with defending yourself, anyway, and IANAL so my legal advice is probably worthless]