...and your comment represents the absolutely fundamental misunderstanding that pervades this discussion.
The truth no one wants to hear:
The distinction is no longer the technology or the place, but the person(s) using a capability: the target. In a free society based on the rule of law, it is not the technological capability to do a thing, but the law, that is paramount.
Gone are the days where the US targeted foreign communications on distant shores, or cracked codes used only by our enemies. No one would have questioned the legitimacy of the US and its allies breaking the German or Japanese codes or exploiting enemy communications equipment during WWII. The difference today is that US adversaries -- from terrorists to nation-states -- use many of the same systems, services, networks, operating systems, devices, software, hardware, cloud services, encryption standards, and so on, as Americans and much of the rest of the world. They use iPhones, Windows, Dell servers, Android tablets, Cisco routers, Netgear wireless access points, Twitter, Facebook, WhatsApp, Gmail, and so on.
US adversaries now often use the very same technologies we use. The fact that Americans or others also use them does not suddenly or magically mean that no element of the US Intelligence Community should ever target them. When a terrorist in Somalia is using Hotmail or an iPhone instead of a walkie-talkie, that cannot mean we pack our bags and go home. That means that, within clear and specific legal authorities and duly authorized statutory missions of the Intelligence Community, we aggressively pursue any and all possible avenues, within the law, that allow us to intercept and exploit the communications of foreign intelligence targets.
If they are using hand couriers, we target them. If they are using walkie-talkies, we target them. If they are using their own custom methods for protecting their communications, we target them. If they are using HF radios, VSATs, satellite phones, or smoke signals, we target them. If they are using Gmail, Windows, OS X, Facebook, iPhone, Android, SSL, web forums running on Amazon Web Services, etc., we target them -- within clear and specific legal frameworks that govern the way our intelligence agencies operate, including with regard to US Persons.
That doesn't mean it's always perfect; that doesn't mean things are not up for debate; that doesn't mean everyone will agree with every possible legal interpretation; that doesn't mean that some may not fundamentally disagree with the US approach to, e.g., counterterrorism. But the intelligence agencies do not make the rules, and while they may inform issues, they do not define national policy or priorities.
Without the authorities granted by the FISA Amendments Act of 2008 (FAA), the United States cannot target non-US Persons who are foreign intelligence targets if their communications enters, traverses, or otherwise touches the United States, a system within the United States, or, arguably, a system or network operated by a US corporation (i.e., a US Person) anywhere in the world. FAA in particular is almost exclusively focused on non-US Persons outside the US, who now exist in the same global web of digital communications as innocent Americans.
Without FAA, the very same Constitutional protections and warrant requirements reserved for US Persons would extend to foreign nations and foreign terrorists simply by using US networks and services â" whether intentionally or not. Without FAA, an individualized warrant would be required to collect on a foreign intelligence target using, say, Facebook, Gmail, or Yahoo!, or even exclusively foreign providers if their communications happens to enter the United States, as 70% of international internet traffic does. If you do not think there is a problem with this, there might be an even greater and more basic misunderstanding about how foreign SIGINT and cyber activities fundamentally must work.
If you believe NSA should not have these capabilities, what you are saying is that you do not believe the United States should be able to target foreign intelligence targets outside the United States who, by coincidence or by design, ever utilize or enter US systems and services. If you believe the solution is an individualized warrant every time the US wishes to target a foreign adversary using Gmail, then you are advocating the protection of foreign adversaries with the very same legal protections reserved for US citizens -- while turning foreign SIGINT, which is not and never has been subject to those restrictions, on its head.
These are the facts and realities of the situation. Any government capability is imperfect, and any government capability can be abused. But the United States is the only nation on earth which has jammed intelligence capabilities into as sophisticated and extensive a legal framework as we have. When the intelligence committees of both houses of Congress, multiple executive agencies under two diametrically opposite Presidential administrations, armies of lawyers within offices of general counsel and and inspectors general, and federal judges on the very court whose only purpose is to protect the rights of Americans under the law and the Constitution in the context of foreign intelligence collection are all in agreement, then you have the judgment of every mechanism of our free civil society.
Or we could just keep laying our intelligence sources, methods, techniques, and capabilities bare to our enemies.
âMany forms of Government have been tried and will be tried in this world of sin and woe. No one pretends that democracy is perfect or all-wise. Indeed, it has been said that democracy is the worst form of government except all those other forms that have been tried from time to time." - Winston Churchill (1874-1965), Speech in the House of Commons, November 11, 1947
"The necessity of procuring good Intelligence is apparent and need not be further urged â" all that remains for me to add, is, that you keep the whole matter as secret as possible. For upon Secrecy, Success depends in most Enterprises of the kind, and for want of it, they are generally defeated, however well planned and promising a favourable issue.â â" George Washington, our nation's first spymaster, in a letter to Colonel Elias Dayton, 26 July 1777