BERLIN In a crescendo of anger over American espionage, Germany expelled the CIAs top operative, launched an investigation of the vast U.S. surveillance programs exposed by Edward Snowden and extracted an apology from President Obama for the years that U.S. spies had reportedly spent monitoring German Chancellor Angela Merkels cellphone.

In an address to Parliament last year, Merkel warned that U.S.-German cooperation would be curtailed and declared that trust needs to be rebuilt.

But the cooperation never really stopped. The public backlash over Snowden often obscured a more complicated reality for Germany and other aggrieved U.S. allies. They may be dismayed by the omnivorous nature of the intelligence apparatus the United States has built since the Sept. 11, 2001, attacks, but they are also deeply dependent on it.

Over the past year, Germany has secretly provided detailed information to U.S. spy services on hundreds of German citizens and legal residents suspected of having joined insurgent groups in Syria and Iraq, U.S. and German officials said.

Germany has done so reluctantly to enlist U.S. help in tracking departed fighters, determining whether they have joined al-Qaeda or the Islamic State and, perhaps most importantly, whether they might seek to bring those groups violent agendas back to Germany.

The stream of information includes names, cellphone numbers, e-mail addresses and other sensitive data that German security services ever mindful of the abuses by the Nazi and Stasi secret police have been reluctant even to collect, let alone turn over to a suspect ally.

A senior German intelligence official compared the U.S. relationship to a dysfunctional marriage in which trust has bottomed out but a breakup is not an option. Amid what Germans see as evidence of repeated betrayal, the question remaining is whether the husband is a notorious cheater or can be faithful again, said the official, who like others interviewed for this article spoke on the condition of anonymity to discuss intelligence matters. Were just going to have to give it another try. There is no alternative. Divorce is out of the question.

More than 550 German citizens have gone to Syria, officials said, and at least nine have killed themselves in suicide attacks.

The exodus is part of a much broader flow of more than 15,000 foreign fighters who have entered Syria over the past four years from 80 countries. At least 3,000 of them are from Europe the largest contingent of Islamist jihadists with Western passports that counterterrorism agencies have ever faced.

As a result, nearly every country in Europe is turning over significant data on their own departed fighters to the United States. Some of these nations, including Germany, have capable security and intelligence agencies of their own. But even their combined resources probably cannot match the scope and reach of their U.S. counterparts.

See the rest here:

Backlash in Berlin over NSA spying recedes as threat from Islamic State rises