Foreign secretary Boris Johnson announced on Monday that Jeremy Fleming, the deputy director-general of MI5, will take over as GCHQ director-general "around Easter".
The announcement follows the unexpected decision by current director-general Robert Hannigan earlier this year to stand down for personal reasons, after just two years in the post.
Fleming – described as "whip smart" by one person contacted by BuzzFeed News – will take over the role just weeks after White House press secretary Sean Spicer accused the agency of "wiretapping" Donald Trump on behalf of the Obama administration.
The move led to an angry – and highly unusual – public denial from GCHQ, and a subsequent back-and-forth between the UK and US to try to calm the row.
Managing this fraught relationship with the US will be one of the top priorities for Fleming as he starts his new role next month, as GCHQ and its American counterpart, the National Security Agency, are hugely reliant on one another to maintain their surveillance capabilities across the world.
Fleming's career has focused largely on the domestic stage. MI5 – the Security Service – is responsible for counterintelligence and countering homegrown threats, while GCHQ's focus is on the bulk interception of communications networks across the world.
But a description of his career issued alongside his appointment states he has worked on MI5's technical capabilities, internationally and on Northern Ireland.
Fleming also worked for a time reshaping the government's counterterrorism strategy, Contest, which created and then expanded the controversial Prevent programme. Prevent seeks to prevent radicalisation, but has been criticised by Muslim and civil liberties groups as a virtual surveillance programme on the Muslim population.
On Twitter, GCHQ's director of communications Andrew Pike welcomed the appointment.
BuzzFeed News understands Fleming was also in the running to be the first director-general of the National Crime Agency – which leads on serious and organised crime – in 2011, before the role went to Keith Bristow.
In a statement released alongside the announcement of his hire, Fleming said he would continue the work of his predecessor to increase the transparency of GCHQ's operations.
"I’d like to pay tribute to Robert Hannigan, who over the last few years has led GCHQ through the transformation of some of our most important national security capabilities," he said.
"I look forward to building on his legacy and in particular, the role he has played in increasing the transparency of GCHQ’s crucial work and in expanding its cyber mission through the work of the National Cyber Security Centre."
James Ball is a special correspondent for BuzzFeed News and is based in London. PGP: here
Contact James Ball at James.Ball@buzzfeed.com.
Got a confidential tip? Submit it here.