France and Germany have said they want a "no spying" pact with America by the end of the year.
Germany's leader, Angela Merkel, said this week that spying on friends is "really not on" after claims her mobile phone had been bugged by US agents.
And today, a report in the Guardian newspaper claims America had been monitoring the phone calls of at least 35 world leaders.
But US officials say that at the moment, they're doing nothing wrong.
Earlier today, Prime Minister David Cameron was asked whether British spy agencies had been involved in bugging Britain's EU partners.
British and American spies do work closely together - but Mr Cameron answered that he was satisfied that the UK's agencies are properly run and act under the law.
Spying's not unusual
Countries do routinely spy on each other, especially if they are enemies, but Angela Merkel has said spying shouldn't happen between countries who are "friends".
Speaking at a meeting of European leaders yesterday, Mrs Merkel said: "We need trust among allies and partners. Such trust now has to be built anew.
She continued: "The United States of America and Europe face common challenges. We are allies. But such an alliance can only be built on trust. That's why I repeat again: spying among friends, that cannot be."
There are now worries that these spying claims could affect the trust between the US and European countries - and how effectively they work together in their aim to fight terrorism.
Monitoring other countries can help in war situations or to prevent acts of terrorism but there are questions about justifying which people should be watched.
The United States already has a "no-spying" deal with Britain, Australia, New Zealand and Canada, that was arranged after World War Two.
Now Germany and both France say they want a no spying pact with the US as well.