The US and UK are to simulate large scale cyber-attacks on a variety of sectors in a bid to better prepare and tackle future online cybersecurity breaches.
The UK government confirmed the first exercise will involve a simulated cyber-attack on the financial sector in 2015.
In 2014, around 20 British banks and financial firms underwent a major round of cyber warfare simulations in a bid to test their resilience against hacking attacks.
However, this "unprecedented" arrangement between the US and UK has been agreed after the devastating cyber-attack hackers enacted on Sony Pictures last year.
"GCHQ has massive expertise [in fighting cyber-attacks] ", said UK Prime Minister David Cameron to the press in Washington, as part of his two-day visit to the country before the May general election.
"Cyber-attacks is one of the big modern threats that we face. This is a real signal it's time to step up the efforts and to do more.
"It's also about protecting people's data, people's finances - these attacks can have real consequences to people's prosperity."
US President Barack Obama added that cybersecurity threats were an "urgent and growing danger".
The UK government confirmed both countries would be operating "cyber-cells" and Britain's MI5 and the US' FBI would be working closely together.
Last year, Sony Pictures was hit by a vast cyber security breach that has led to unidentified hackers leaking unreleased movies, emails between senior executives and confidential information relating to members of staff.
This includes social security numbers, salaries, healthcare records, performance evaluations and reasons for termination.
According to PwC's 2014 global economic crime survey, 39% of financial services companies were hit by cyber attacks, compared with only 17% of firms in other industries. But, according to the UK government's 2013 Information Security Breaches Survey, those figures are much higher.
That report suggests 93% of large organisations and 87% of small businesses suffered a security breach during 2013, with the median number of breaches for a large organisation sitting at 113, while for small organisations it was 17.