Trying to remember back to Snowden, I think I recall that not only DON'T they have such an agreement, but the intelligence folks consider this a feature. The US government is Constitutionally forbidden from reading "US persons" communications, but our Constitution has no such restriction on third parties. So if those third parties do the spying for us, and then tell our intelligence folks about it, everybody wins. Well, except for the people.
I think it's just more likely that we send them whatever they ask for when they ask for it.
It's cute, really. Country A turns a blind eye and even helps country B vacuum all of it's citizen's data. Then country B gifts back to A. And vice versa.
Since country A didn't do the surveillance, it didn't break any laws. Furthermore, it's legal to accept data from third parties.
As to why country A would allow even its senators and congressmen to be spied on by B? That's obvious - country A's intel agencies are most interested in their budget!
But this is a special case. It's Israel.
And laws are also written extremely broadly, which gives the intelligence agencies extreme leeway in interpreting them as they see fit. And even if they go beyond that, it's not like there are any consequences. For one of the most overt - James Clapper indisputably lied under oath and absolutely nothing happened. Furthermore politicians are generally ignorant on most topics, especially on anything remotely technically related. But revealing that ignorance is politically damaging, so they turn into yes men on most of these topics.
> Since country A didn't do the surveillance, it didn't break any laws.
Of course it did, that's where the data came from!
2. The power of the constitution ends at the border.
It's pretty sick, but that's what it amounts to. The CIA can't operate within US borders but it can operate at and outside borders. That means sending messages internationally are fair game for warrant-less searches.
This means that they can read even the personal email of Supreme Court justices, congressmen and senators.
However they have a gentleman’s agreement to not do that.
“Wink”