The CIA has curbed spying on friendly governments in Western Europe in response to the furor over a German caught selling secrets to the U.S. and the Edward Snowden revelations of classified information held by the National Security Agency, according to current and former U.S. officials.

The pause in decades of espionage, which remains partially in effect, was designed to give CIA officers time to examine whether they were being careful enough and to evaluate whether spying on allies is worth running the risk of discovery, said a U.S. official who has been briefed on the situation.

Under the stand-down order, case officers in Europe largely have been forbidden from undertaking 'unilateral operations' such as meeting with sources they have recruited within allied governments. Such clandestine meetings are the bedrock of spying.

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NSA whistleblower Edward Snowden, pictured last October, was granted a Russian residency permit last month. Among his revelations, he revealed that the U.S. had tapped the phone of German leader Angela Merkel, causing tension between the two countries

CIA officers are still allowed to meet with their counterparts in the host country's intelligence service, conduct joint operations with host country services and conduct operations with the approval of the host government.

Recently, unilateral operations targeting third country nationals, Russians in France, for example, were restarted. But most meetings with sources who are host nationals remain on hold, as do new recruitments.

The CIA declined to comment.

James Clapper, the U.S. director of national intelligence, said during a public event on Thursday that the U.S. is assuming more risk because it has stopped spying on 'specific targets,' though he didn't spell out details.

Spying stand-downs are common after an operation is compromised, but 'never this long or this deep,' said a former CIA official, who, like others interviewed for this story, spoke on condition of anonymity because it's illegal to discuss classified material or activities.

NSA leaks revealed that the U.S. agency had tapped German leader Angela Merkel's phone, making for an awkward exchange with President Obama

The pause, which has been in effect for about two months, was ordered by senior CIA officials through secret cables.

The current stand-down was part of the fallout from the July 2 arrest of a 31-year-old employee of the German intelligence service. Suspected of spying for Russia, he told authorities he passed 218 German intelligence documents to the CIA.

In a second case, authorities searched the home and office of a German defense official suspected of spying for the U.S., but he denied doing so, and no charges have been filed against him.

A few days later, Germany asked the CIA station chief in Berlin to leave the country, an unprecedented demand from a U.S. ally.

The move demonstrated how seriously the Germans were taking the situation, having already been stung by revelations made by Snowden, a former NSA systems administrator, that the agency had tapped German chancellor Angela Merkel's mobile phone.

The NSA disclosure infuriated Merkel, who demanded explanations from President Barack Obama. It embarrassed both world leaders and has left many Germans skeptical about cooperating with the U.S.

CIA managers were worried that the incident could lead European security services to begin closely watching CIA personnel. Many agency officers in Europe, operating out of U.S. Embassies, have declared their status as intelligence operatives to the host country.

The spying stand-down comes at an inopportune time, with the U.S. worried about Europeans extremists going to fight in Syria, Europe's response to Russian aggression and European hostility to American technology companies following revelations the companies turned over data to the NSA.

While the U.S. cooperates closely with Europe against terrorism, spying can help American officials understand what their allies are planning and thinking, whether about counterterrorism or trade talks.

The 'EUR' division, as it is known within the CIA, covers Canada, Western Europe and Turkey. While spying on Western European allies is not a top priority, Turkey is considered a high priority target — an Islamic country that talks to U.S. adversaries such as Iran, while sharing a border with Syria and Iraq. It was not known to what extent the stand-down affected operations in Turkey.

European countries also are used as safe venues to conduct meetings between CIA officers and their sources from the Middle East and other high priority areas. Those meetings have been rerouted to other locales while the pause is in place.

The European Division staff has long been considered among the most risk-averse in the agency, several former case officers said, speaking on condition of anonymity because they weren't authorized to discuss secret intelligence matters by name.

A former CIA officer who worked under non-official cover wrote a 2008 book in which he described a number of operational 'stand- downs,' in Europe, including one in France in 1998 because of the World Cup soccer championship, and another in a European country in 2005, in response to unspecified security threats.

The former officer, whose true name has not been made public, wrote 'The Human Factor: Inside the CIA's Dysfunctional Intelligence Culture,' under a pseudonym, Ishmael Jones. He is a former Marine who served 15 years in the agency before resigning in 2006.

The CIA acknowledged his status as a case officer when it successfully sued him for publishing the book without first submitting it for pre-publication censorship, as he was required to do under his secrecy agreement.

The CIA last faced that sort of blowback from a European ally in 1996, when several of its officers were ordered to leave France.

An operation to uncover French positions on world trade talks was unraveled by French authorities because of poor CIA tactics, according to a secret CIA inspector general report, details of which were leaked to reporters.