The NSA/CIA will only buy an 0day if they can use it. They can't use it if they disclose the bug.
I point this out, yet again, because of this WaPo article [*] built on the premise that the NSA/CIA spend millions of dollars on 0day they don't use, while unilaterally disarming tiself. Since that premise is false, the entire article is false. It's the sort of article you get when all you interview are Washington D.C. lobbyists and Washington D.C. politicians -- and no outside experts.
It quotes former cyberczar (under Obama) Michael Daniel explaining that the "default assumption" is to disclose 0days that the NSA/CIA get. This is a Sean Spicer style lie. He's paid to say this, but it's not true. The NSA/CIA only buy 0day if they can use it. They won't buy 0day if the default assumption is that they will disclose it. QED: the default assumption of such 0day is they won't disclose them.
The story quotes Ben Wizner of the ACLU saying that we should patch 0days instead of using them. Patching isn't an option. If we aren't using them, then we aren't buying them, and hence, there are no 0days to patch. The two options are to not buy 0days at all (and not patch) or buy to use them (and not patch). Either way, patching doesn't happen.
Wizner didn't actually say "use them". He said "stockpiling" them, a word that means "hold in reserve for use in the future". That's not what the NSA/CIA does. They buy 0days to use, now. They've got budgets and efficiency ratings. They don't buy 0days which they can't use in the near future. In other words, Wizner paints the choice between an 0day that has no particular value to the government, and one would have value being patched.
The opposite picture is true. Almost all the 0days possessed by the NSA/CIA have value, being actively used against our adversaries right now. Conversely, patching an 0day provides little value for defense. Nobody else knew about the 0day anyway (that's what 0day means), so nobody was in danger, so nobody was made safer by patching it.
Wizner and Snowden are quoted in the article that somehow the NSA/CIA is "maintaining vulnerabilities" and "keeping the holes open". This phrasing is deliberately misleading. The NSA/CIA didn't create the holes. They aren't working to keep them open. If somebody else finds the same 0day hole and tells the vendor (like Apple), then the NSA/CIA will do nothing to stop them. They just won't work to close the holes.
Activists like Wizner and Snowden deliberate mislead on the issue because they can't possibly win a rational debate. The government is not going to continue to spend millions of dollars on buying 0days just to close them, because everyone agrees the value proposition is crap, that the value of fixing yet another iPhone hole is not worth the $1 million it'll cost, and do little to stop Russians from finding an unrelated hole. Likewise, while the peacenicks (rightfully, in many respects) hate the militarization of cyberspace, they aren't going to win the argument that the NSA/CIA should unilaterally disarm themselves. So instead they've tried to morph the debate into some crazy argument that makes no sense.
This is the problem with Washington D.C. journalism. It presumes the only people who matter are those in Washington, either the lobbyists of one position, or government defenders of another position. At no point did they go out and talk to technical experts, such as somebody who has discovered, weaponized, used an 0day exploit. So they write articles premised on the fact that the NSA/CIA, out of their offensive weapons budget, will continue to buy 0days that are immediately patched and fixed without ever being useful.