Jim Dempsey, vice president for public policy at the Center for Democracy and Technology (CDT), said he is not sure if the questions raised about American cloud providers in Europe are truly about privacy. "Is this a privacy issue? Or do governments want to keep the access to data in their own hands?" he said in a phone interview.

According to Dempsey, every country in the world has its own version of the Patriot Act. "No company in the world can guarantee that it will not disclose information to governments," he said. The Dutch government itself could easily decide to turn over information to the U.S. "Also the Dutch government is likely to demand access to data of Dutch citizens stored in the U.S.," he said.

In the meantime, U.S. cloud providers tiptoe around the subject. Neither Microsoft nor Google were willing to comment on the issue, and IBM and Amazon did not immediately respond to questions. The White House press office also remained silent on the matter.

(René Schoemaker from Webwereld.nl contributed with this story.)