WASHINGTON (AP) — In geopolitics, just as on the playground, even best friends don’t tell each other everything. And everybody’s dying to know what the other guy knows.

Revelations that the U.S. has been monitoring the cellphone calls of up to 35 world leaders have brought into high relief an open-yet-often-unspoken secret — allies spy on allies. It’s also raised a question: With the incredible reach of new-millennium technology, is this still OK?