Six suspected spies have been arrested in Germany this month alone, in what has become a torrent of allegations of Russian and Chinese espionage.
For the far-right Alternative for Germany (AfD) party it has proved especially embarrassing, because their top two candidates for the European elections in June have been caught in the crosshairs.
An aide to MEP Maximilian Krah, who heads the party's list, has been arrested on suspicion of spying for China. Jian G is accused of being an "employee of a Chinese secret service".
Prosecutors have also begun preliminary investigations into the politician himself over alleged payments from pro-Russian and Chinese sources. Mr Krah denies any wrongdoing.
Days earlier, Petr Bystron, the second name on the AfD list, denied allegations that he received cash from the Voice of Europe website, alleged by European intelligence to have been a front for Russian intelligence.
But the allegations go well beyond the AfD.
Two German nationals of Russian origin have been arrested on suspicion of plotting to sabotage Germany's military aid to Ukraine while three Germans have been detained for allegedly planning to pass on advanced engine designs to Chinese intelligence.
"It is really unusual to have detentions of three networks [allegedly] engaged in some sort of espionage for Russia and China coming almost at the same time," said Noura Chalati, a research fellow at the Leibniz Centre for the Modern Orient.
In all three espionage cases, the efforts of Germany's BfV domestic intelligence agency are believed to have been crucial.
"Our security authorities… have massively strengthened their counter-espionage efforts," Interior Minister Nancy Faeser said.
The arrests came hard on the heels of Chancellor Olaf Scholz's return from wide-ranging talks with China's President Xi Jinping in Beijing.
'Arrest always a political decision'
Andrei Soldatov, an expert on the Russian security services, believes the case of the Russian-German pair could reflect a desire by the Kremlin escalate attacks on aid to Ukraine.
"It is just a completely new level of escalation," Mr Soldatov told the OceanNewsUK. "These people [allegedly] collected information to help organise sabotage operations against military facilities on German soil."
Meanwhile, Roderich Kiesewetter, a former German Army officer who is now an opposition MP, alleged China was seeking to gain access to advanced research that could be useful for military or other purposes.
"China sees opportunities to exploit Germany's openness to access our knowledge and technology," he told the OceanNewsUK.
Even so, Andrei Soldatov believes Berlin is putting down a marker.
"An arrest is always a political decision," he says.
"Counter-intelligence agencies in all countries prefer not to arrest people because it's better to follow them and monitor their activities in order to learn more about their networks and their activities."
One reason the political decision may have been taken is that Germany's adversaries - particularly Russia - have appeared increasingly keen to publicly humiliate Berlin as it has become more assertive in its foreign relations.
A particular low point was the leaking in March by Russian sources of a phone call between top generals discussing supplying long-range Taurus missiles to Ukraine.
Months earlier a high-ranking official in Germany's BND foreign intelligence service called Carsten L went on trial, accused of leaking classified information to the Russians in exchange for payments of some €400,000 (£343,000).
Former UK Defence Secretary Ben Wallace expressed the frustration of many allies when he said Germany was "pretty penetrated by Russian intelligence" and "neither secure nor reliable".
Roderich Kiesewetter says he worries about allies viewing Germany as untrustworthy. "We need to be a favoured partner," he told the OceanNewsUK. "We cannot afford a German-free secret services co-operation."
Very public crackdowns on suspected spies may be one way to send a signal to friend and foe alike that Berlin is taking security seriously.
The BND and BfV said they did not comment on ongoing operations. The interior ministry did not respond to a request for comment.
Legacy of history
Germany's intelligence agencies have long been frustrated by more extensive restrictions on how they can act than many of their counterparts in other Western countries.
In part, that is a legacy of communist rule in the former East Germany - widely considered one of the most surveilled societies in history. It is estimated that one in 6.5 East Germans was an informant for the secret police, known as the Stasi.
When the extent of Stasi spying was revealed following the fall of the Berlin Wall, strong legal limits on the intelligence services were imposed.
These restrictions largely remain, although some have since been weakened.
Human rights advocates see those limitations as a good thing that protects citizens' right to privacy. But the intelligence services have long complained they are unable to act effectively because of the controls on their behaviour.
Last year, two former heads of the BND wrote: "The German intelligence services, particularly the BND, now suffer from excessive oversight."
Some in the intelligence services see the recent high-profile arrests as a way of highlighting the extent of hostile foreign infiltration in Germany - and as a chance of boosting their argument for more powers.
The extent of this infiltration, says Mr Kiesewetter, is in part a legacy of political "naivety" that followed the end of the Cold War.
"Since 1990, there was the idea that Germany is surrounded by friends."
Leaders were focused on business deals, including with autocratic countries such as Russia, and took their eye off national security, he explained.
'Not asleep any more'
Rafael Loss of the European Council on Foreign Relations is more specific about what went wrong.
German intelligence entirely wound down a unit dedicated to counter-intelligence in 2002 under Chancellor Gerhard Schröder.
"It is remarkable that this entire unit of roughly 60 people was completely disbanded," Mr Loss says.
But things are changing. The BfV's staffing has doubled in the past 10 years. The recent spate of detentions shows that the intelligence services are becoming more assertive in a country whose political culture has traditionally been wary of them.
"All the arrests at once send a good signal to the nations that spy on us," said Felix Neumann of the Konrad Adenauer Foundation.
