The leader of Britain's domestic spy agency is scheduled to deliver a speech Monday in Berlin to his European counterparts, the first speech ever made outside Britain by a serving MI5 chief.
In the rare public address, Andrew Parker will say close cooperation among the European spy agencies is vital as they all face threats from the Islamic State and and Russia.
He will warn the group they are facing "devastating and more complex attacks" from the Islamic State and "aggressive and pernicious actions" from Russia that risk making Russia a "more isolated pariah."
Partial remarks of the landmark address have been released, revealing that Parker will also say Russia is committing "flagrant breaches of international rules."
Parker is making the address as Britain prepares to leave the European Union. He will say, however, that "European intelligence cooperation today is simply unrecognizable to what it looked like five years ago," and adding that "In today's uncertain world we need that shared strength more than ever."
The event is Berlin is being hosted by Germany's BfV domestic intelligence service.