Editor's note: Charlotte Potts is a German national who has worked as a journalist and producer for both major German TV networks, ARD and ZDF, in Washington, DC. She reported on the 2008 and 2012 US campaigns and elections for a German audience and currently covers politics and society across the US. Follow her on Twitter @charlottecpotts
Washington (CNN) -- Angela Merkel might be the most powerful female politician in the world these days. She certainly is in Europe. We now know that her cell phone was monitored by U.S. intelligence, not just since she became the German Chancellor in 2005, but also for an additional three years before that.
Many U.S. analysts are now arguing that Merkel's anger at the revelations is manufactured for public consumption. They could not be more wrong.
A lot of Germans were flustered when they learned this summer that the NSA had been collecting millions of bits of so-called meta-data on them. According to opinion polls, 60% of Germans supported Edward Snowden's release of classified information. Just 17% found what he did was wrong.
For Germans, the discussion about U.S. surveillance is not a joke. In fact, it couldn't be more serious. We value our privacy highly. It is seen as an individual liberty that often could not be taken for granted in German history. Both the Nazi secret police -- the Gestapo -- and the East German intelligence agency -- the Stasi -- spied extensively on citizens.
Even in more recent decades Germans have repeatedly fought battles about privacy and against a perceived "Überwachungsstaat" -- or "surveillance state." Compared to the U.S., Germany already has many laws concerning data privacy, but two-thirds of Germans would even like stricter regulations.
Back in the summer, Merkel tried to downplay the U.S. surveillance herself and stood strong on the side of the U.S. ally. In mid-July, Merkel gave an interview on the topic, which in light of the recent revelations, seems almost satirical.
The host of the show introduced her as "the lady who hopes that at least her cell phone is bug-proof, even from U.S. intelligence services." Merkel said later in the interview: "I know that I am not being monitored."
A month later -- and in the midst of an election campaign dominated by this issue -- the German government announced that the "NSA scandal," as the German media called it, was over because the U.S. had ensured more transparency. The German public's anger calmed and Merkel cruised to re-election.
Last week Merkel learned in a particularly personal way that the issue is far from over.
She became Germany's first NSA victim known by name and gave the extent of U.S. spying a face.
Politically Merkel didn't have a lot to gain by bringing this issue to the table again. Her anger is not simulated for domestic consumption. In fact, the opposite is true, since she is now criticized for not taking the extent of the surveillance more serious in the beginning.
Merkel is usually measured. For her to pick up the phone and call President Barack Obama to publicly criticise the extent of U.S. surveillance shows how disgruntled she really is. Her anger seems real and rightfully so.
Eavesdropping on Merkel's conversations and reading her text messages is completely unacceptable. Not because she is the most powerful female politician, but because she is one of the closest allies the U.S. has in Europe and, overall, a trusted friend.
Back in the summer, Obama said that if he wanted to know what Merkel is thinking, he could pick up the phone and just ask her.
In retrospect, this comment verges on the offensive. So what benefit does it really bring to spy on Germany? Are these benefits really worth the costs? Even if Obama has begun a foreign policy shift towards Asia in his presidency, he still needs strong transatlantic partners.
Of course, the "Handyüberwachung" -- the German word for spying on cell phones -- hits close to home for Merkel.
She grew up in Eastern Germany where every conversation, every step, was monitored by the Stasi.
It's in part because of her past that Merkel always had a lot of respect for the United States. She values freedom and liberties and with that the country, which seemed to value these attributes the most: The United States.
Merkel wouldn't challenge relationships with the U.S. if she didn't think it was necessary. She wouldn't endanger the Swift data exchange agreement and negotiations on a free trade zone between the European Union and the United States, just to demonstrate that she is a strong leader or to strengthen her position at home, which is stable regardless at the moment.
Ever since World War II, German-U.S. relations have flourished through trust in each other. That trust is broken now. For the first time it seems, the U.S. has crossed an actual threshold.
Tapping the phones of ally leaders shouldn't be a question of "can we", but rather "should we?"
Now it is time for the U.S. to try to understand those cultural concerns, to show Europeans that security doesn't trump liberty; that the intelligence services haven't gone wild and, especially, to rebuild the trust of a valued ally.
The opinions expressed in this commentary are solely those of Charlotte Potts