In a joint press conference at the White House yesterday, the US president said there should not be an “overreaction” to the atrocities in Paris.
He also suggested European countries needed to make sure their Muslim populations were better “assimilated”.
The comments came after a two-day visit by the Prime Minister in which he pushed for tougher requirements for internet firms to alert authorities to suspicious online exchanges, ban encrypted communications and store data.
A report last year into the murder of Fusilier Lee Rigby concluded Facebook failed to pass on information that could have prevented his death. The US firm had previously shut down accounts belonging to one of the killers, Michael Adebowale, because he had discussed terrorism – but did not raise security concerns.
The two leaders agreed to establish a new joint group to exchange information and expertise on countering the rise of violent extremism.
But the premiers conceded there was still more work to be done to find a way of ensuring suspected terrorists can be tracked without undermining civil liberties.
Mr Cameron said: “I take a very simple approach to this, which is ever since we’ve been sending letters to each other or making telephone calls to each other or mobile phone calls to each other or, indeed, contacting each other on the internet, it has been possible in both our countries in extremis; in my country by signed warrant by the Home Secretary, to potentially listen to a call between two terrorists, to stop them in their activity.
“In your country, a judicial process. We’ve had our own. We’re not asking for back doors. We have – we believe in very clear front doors through legal processes that should help to keep our country safe.”
Mr Obama said: “What we have to find is a consistent framework whereby our publics have confidence that their government can both protect them but not abuse our capacity to operate in cyber space.”