DW: What is the National Security Agency (NSA) capable of - or rather, what can't they do?

Erich Schmidt-Eenboom: The Federal Office for Information Security (BSI) in Bonn attempts to protect government communication. It is responsible for encryption technology, not only for the chancellor but also for the ministers, state secretaries, all government agencies. But all the IT experts in Germany agree that it's nearly impossible to defend against the massive capacities of the NSA and its advanced technology. If they want to break through the encryption somewhere, then they can do it. Their orders come from the White House; the president decides what intelligence objectives are to be pursued. In this respect, it's not really an NSA scandal, but an Obama scandal.

Who is responsible for counterintelligence in Germany?

For counterintelligence, the monitoring of the activities of foreign intelligence services in Germany, it's the Federal Office for the Protection of the Constitution (BfV) that's responsible. The technical security of government communications is the responsibility of the BSI, which attempts to protect communication with the appropriate encryption. Since the beginning of the last century, we have actually experienced a constant race between encryption and decryption experts. And that has mostly worked in the favor of those who want to access data, in this case the NSA.

Would you say that the BfV and the BSI do their job well?

From a technical standpoint, the BSI is certainly world-class. Concerning the BfV, there are also political demands. And until now there hasn't been any political direction to defend the country from all sides. Counterintelligence must become more active in every direction - even in the West, with an emphasis on the US and Britain.

Why was this not done up until now?

That was due to political considerations. The German government has always known that it was in the crosshairs of the American intelligence services, but the topic has never really been addressed. Pressure for action only arose after the revelations by [former NSA analyst Edward] Snowden. Politicians tried to dismiss the topic, to keep it behind the scenes. But with the recent developments and the personal involvement of the chancellor, of course, the subject has gained new political weight.

How securely encrypted is the chancellor's mobile phone?

The manufacturer of this encryption technology swears that the system cannot be cracked. But if you ask the leading encryption experts at German universities, then they say that it was only a matter of time before the NSA gained access. From a purely technical standpoint, counterintelligence work is very hard.

Is Germany able to protect itself against the NSA spying?

Only through binding international treaties with the United States, which exclude mutual spying in the political and economic arenas. Something like this was already tried in 2010, between France and the US. At the time, the French foreign intelligence service and the CIA had negotiated an agreement, which only failed after personal resistance from President Obama. This proves, however, that it is politically possible.

When would be a good time to negotiate such an agreement?

There is now an historic opportunity. Many are now demanding that such an agreement be tied to the free trade agreement negotiations. This is a means to pressure the Americans, who are very keen to establish this free trade area. In addition, there is now a particularly favorable environment because the NSA affair has also sparked indignation in France, which strengthens the possibilities for action within the European Union.

Would it also be possible for German intelligence agencies to spy on foreign heads of state?

The Federal Intelligence Service (BND) is technically a very good intelligence service, because it has the appropriate technology base in Germany. There are many top German companies that excel in manufacturing monitoring technology. However, the BND has a very strict political restrictions that do not allow spying. The BND focuses on its core tasks: the fight against international terrorism, the support of Germany's military operations and the fight against organized crime. It does not spy on allied governments.

Erich Schmidt-Eenboom is a well-known secret service expert and was described by the weekly newspaper "Die Zeit" as someone who "watches the watchers." He is head of the Research Institute for Peace Policy in Bavaria.