18:14 16 January 2015
Prime Minister David Cameron and President Barack Obama, who have discussed the need to intercept internet communications, have agreed to stage fake cyber war games to boost both countries’ resistance to cyber attacks.
It is expected that the two nations will share an unprecedented amount of intelligence and information in order to realise their goal.
The Prime Minister has said: "We shouldn't leave a safe space in which terrorists can communicate with each other.
"There is a broad agreement that we need to have powers, in extremis, to intercept communications between terrorists. That is what America does today. It is what Britain does today.
"We share the intelligence and information between us and this has saved countless lives, not just in Britain and America but in other countries as well.
"We must go on sharing that information, both acting under our own legal systems, the legal system in America is different to the one here."
Under the plans, GCHQ and MI5 will work together with the FBI and National Security Agency to create a rolling programme of simulated war games involving attacks on the City and Wall Street to test their resilience.