Just as tensions had begun to recede between Germany and the US over NSA activities, including the penetration of Chancellor Angela Merkel’s telephone conversations, another spy row threatens the decades-long partnership in Europe. The Germans discovered a mole in their intelligence unit that sold information to American intelligence — and tried to make a few rubles off of the Russians, too:

A German intelligence ‘double agent’ who allegedly sold hundreds of top secret documents to the US was only caught after trying to broker an additional deal with Russia.

Details of the deal, to the Russian secret service, emerged yesterday after Chancellor Angela Merkel’s government summonsed the US ambassador to Berlin.

It is the second case of suspected US intelligence spying against Germany within a year.

The new case relates directly to the original case. Apparently, the US intelligence community wanted an up-close-and-personal look into Germany’s investigation of the NSA:

On Friday, Germany’s Bundesnachrichtendienst (BND) intelligence service admitted that one of its agents had been arrested for supplying American intelligence with at least 300 top secret documents over a period lasting several years, The Independent reported.

Three of the documents are believed to have related to German investigations into US surveillance and phone bugging.

Needless to say, the Germans didn’t take this very kindly. The government in Berlin had already expressed considerable outrage over bugging Merkel, and now they’re hopping mad about US spying on their internal probe. The foreign office called the US ambassador on the carpet over the discovery this weekend, and ministers in Merkel’s government are warning that this might cause a very significant breach in the alliance:

The revelations strained ties between Washington and Germany, a key European ally, which both countries’ leaders have been at pains to repair.

But President Joachim Gauck said in an interview with ZDF to be aired later Sunday that if the latest suspicions are confirmed, “then it probably really has to be said, now it’s enough”, warning that a friendship and close bond were at stake. …

“I expect now for everyone to assist in the speedy clarification of the accusations, and quick and clear statements, also by the US,” Interior Minister Thomas de Maiziere told Bild newspaper in comments released ahead of Monday’s edition. …

The US ambassador was asked to attend a meeting late on Friday at the foreign ministry, following initial media reports that a 31-year-old man arrested last week had been feeding information to a US agency for two years.

Foreign Minister Frank-Walter Steinmeier said in a tweet on Sunday during a visit to Mongolia that the expectation had been expressed to the US envoy that his country help “in clarification as quickly as possible”.

“If reports are correct, we are not talking here about small potatoes,” Steinmeier added.

How unusual is this, though? In the initial leaks from the Edward Snowden cache, John Kerry noted that lots of countries spy on other countries, even their allies. “I will say that every country in the world that is engaged in international affairs and national security undertakes lots of activities to protect its national security and all kinds of information contributes to that,” Kerry said at the time. “All I know is that is not unusual for lots of nations.” A couple of years earlier, CBS News parsed through the Wikileaks cache and discovered massive industrial espionage by France on just about everyone else, especially Germany.

The key is not getting caught. Getting caught not only blows cover, it also forces your allies to react publicly in outrage over the espionage, even though they are likely doing much the same thing. Sometimes, though, that outrage is no pretense, and that was probably true of the revelation of snooping on Merkel’s phone calls, because even in normal tradecraft between allies, that’s pretty … bold. And that probably means that the outrage over snooping on the investigation into that snooping is probably not a pretense, either. Just wait until we get discovered snooping on the molehunt that follows this incident.

How did the US find this source? That’s unclear, but the method of his exposure raises questions about the source and US risk management in this sensitive effort. The spy wanted to expand his income stream by selling data to the Russians, so her, er, emailed their embassy proposing the sale:

The agent has confessed to providing the US with about 200 secret documents over two years. He was paid for the documents.

Spiegel reported that the agent was caught after an email was found by the Verfassungsschutz, the German domestic security agency, in which he offered his services to the Russian secret service. The email led to an investigation which uncovered his work for the US. According to Spiegel, a manipulated weather app was found on his computer, through which it is suspected information was passed to the US authorities. The man remains under arrest.

Sounds like a real charmer. I wonder if the weather app picked up on the shifting winds in this source’s commerce.