MI5 in the 1990s and 2000s
Reforms and the rise of Islamist terrorism
As the Cold War came to an end, terrorist threats from Northern Ireland and states such as Colonel Qadhafi's Libya became priorities for MI5.
Major reforms were put in place and the Service gained its first female Director General. The rise of Islamist terrorism at the end of the 1990s, culminating in the 9/11 attacks in 2001, led to major changes in the way MI5 operated.
How MI5 tackled the threats from the Provisional IRA and state-sponsored terrorism.
Learn more about how MI5 adjusted to a new era of counter-terrorism work.
The story of MI5's transition from counter-espionage to counter-terrorism.
MI5 and the response to the threat of terrorism from extremist Islamist groups.
Why MI5 was founded; the fight against German espionage; how MI5 caught German spy Carl Hans Lody.
The years immediately after the First World War saw MI5's size being reduced drastically as a result of post-war cost-cutting.
During World War II, the Security Service played a key role in combating enemy espionage, intercepting German communications and feeding misinformation back to Germany.
The Second World War ended with Europe divided between the two superpowers, the United States and the Soviet Union.
You can learn more about the history of MI5 at The National Archives. We periodically release files to The National Archives which cover many aspects of our work.