The Post said the process of informing officials about the risk of disclosure is delicate because in some cases, one part of the cooperating government may know about the collaboration, but others may not.
Meanwhile, the government of Germany said Friday that German officials will travel to the U.S. "shortly" for talks about spying allegations, including whether Chancellor Angela Merkel's cellphone was monitored by the NSA.
The heads of Germany's foreign and domestic intelligence agencies will participate in the talks with the White House and NSA, government spokesman Georg Streiter said though he later said the exact composition of the team had yet to be determined.
He did not give a specific date for the trip, saying it was being arranged on "relatively short notice."
Lisa Monaco, assistant to the president for homeland security, wrote in a USA Today op-ed published Friday that "no one disputes the need for careful, thorough intelligence gathering. Nor is it a secret that we collect information about what is happening around the world to help protect our citizens, our allies and our homeland. So does every intelligence service in the world."
"Today's world is highly interconnected, and the flow of large amounts of data is unprecedented," Monaco wrote. "That's why the president has directed us to review our surveillance capabilities, including with respect to our foreign partners. We want to ensure we are collecting information because we need it and not just because we can."
"An ongoing review is the right approach because at the end of the day you want to make sure your resources are being used where you need them the most," Republican Sen. Marco Rubio said on CNN Friday.
"These leaders are responding to domestic pressures in their own country," said Rubio, a member of the Senate Intelligence Committee. " ... Everyone spies on everybody. That's just a fact. Whether they want to acknowledge that publicly or not, every country has different capabilities but at the end of the day, if you are a U.S. government official traveling abroad, you are aware anything you have on your cell phone, iPad, could be monitored by foreign intelligence agencies, including that of your own allies."
"A lot of what you're seeing is for the domestic consumption of their own public," the senator said. "But at the end of the day, everyone knew there was gambling going on in Casablanca."