EU officials are seeking clarification from the US in relation to the latest allegations from whistleblower Edward Snowden.
The former US intelligence analyst claims that the US has bugged and gained access to network computers at EU offices in Brussels and in Washington.
European officials are warning that relations between the pair could change if the allegations are found to be true.
Duncan Bullivant, CEO of Henderson Risk Limited, says spying and espionage has always been a part of diplomatic processes.
"When it comes to negotiations, when it comes to understanding where your allies may stand on certain positions it's always useful to know what is being said behind the scenes, what their opinions are, off the record. What thier diplomatic communications, or thier non-diplomatic communications, are actually saying, and how that compares with the public position they've taken" he said.