This is the understood and expected function of the NSA, isn't it? Collecting signals intelligence from foreign sources? Does anyone honestly believe the Germans aren't regularly trying to figure out ways to listen to American officials' communications? I find the NSA's domestic spying to be appalling... but this is the sort of thing everyone knew the NSA was responsible for since its inception.
But there is a lot to be said for discretion, especially when you're talking about the top echelon of our NATO allies! Even my defenses of NSA have been predicated on the actual need for intelligence collection. This has the corollary that collection without any use should not be sanctioned.
So absent some evidence of our allies conspiring against us in things like WTO negotiations, I don't see a justification for such phone tapping. Even though it's probably legal, was it really the best use of NSA resources? What actionable intel could they have hoped to gain? We're not talking about Medvedev or Putin's phones after all.
Certainly we have known that the NSA has the capability to tap into many international communications circuits, but we've also "known" that such taps are predicated on the national security interests of the United States. So now the question: Was pushing far beyond the envelope worth it? Was causing a boatload of whistleblowers (not just Snowden) to form still beneficial to the U.S. in the end?
I would judge that it was not, at this point. What I'm interested in knowing is when these taps of allied leadership's telephones actually stopped? Specifically, was it only after Snowden's leaks? Did Obama put a stop to it? Sometime in between? All we know at this point is that the U.S. isn't doing it now, and pinky swears not to do so in the future.
As far as the Germans doing it to us... maybe. But the NSA is also responsible for ensuring that they can't break our comms even if we do assume they're trying. But maybe I'm naive but I honestly think they are probably focused more on Russia, Islamists and other threats to Germany, than on what Obama is saying to Boehner.