The threat of espionage (spying) did not end with the collapse of Soviet communism in the early 1990s. Espionage against UK interests still continues and is potentially very damaging.
What is espionage?
Most governments rely on a range of information being gathered to guide their decisions. This is not the same as espionage.
Espionage is the process of obtaining information that is not normally publicly available, using human sources (agents) or technical means (like hacking into computer systems). lt may also involve seeking to influence decision-makers and opinion-formers to benefit the interests of a foreign power.
Open information gathering
The gathering of publicly available information is a routine activity of diplomatic staff, military attachés and trade delegations. They use open sources such as the media, conferences, diplomatic events and trade fairs, and through open contact with host government representatives. This enables them to monitor political, economic and military developments in their host country and brief their own governments. Foreign representatives thereby help their governments to shape their foreign, commercial and military policies. This type of work is not harmful to our national interests. In fact, it often helps us to build good relationships with other nations.
Why espionage is damaging
Espionage focuses on gathering non-public information through covert means. Classified information is kept secret in the first place because its disclosure might harm national security, jeopardise the country's economic well-being or damage international relations. Its sensitivity makes it necessary for us to protect it but also makes it attractive to spies.
If this information is obtained by those with no right to access it, serious damage can be caused. For instance, other countries are seeking technical details of weapons systems so that they can find ways of neutralising our military advantages. Information on key services such as gas, oil and transport could enable terrorists to seriously damage these important economic targets. And the theft of classified technologies could enable foreign companies to copy them, threatening both national security and jobs in the UK.
Countering this threat is therefore a key priority for MI5.
How does MI5 tackle espionage?
MI5 has a branch dedicated to countering espionage and cyber threats. We are also heavily engaged in protective security work, which helps to frustrate both terrorism and espionage.
We seek to find those trying to pass sensitive UK information and equipment to other countries and to ensure they don't succeed. We also investigate and disrupt the actions of foreign intelligence officers where these are damaging to our country’s interests.
Our methods of disruption will vary. Often, it involves alerting someone to a foreign intelligence service's interest in recruiting them. We advise on how to avoid or deal with an approach if it happens.
We also seek to make it more difficult for foreign intelligence services to operate in the UK. We do this by providing security advice to companies and organisations that have sought-after information and equipment.
Occasionally, if a foreign intelligence officer's activities are especially intrusive or threaten real damage to UK interests, they may be required by the Foreign and Commonwealth Office to leave the UK. In the case of some nationalities requiring a visa to enter the UK, MI5 can suggest to the Secretary of State that this is refused for a known intelligence officer.
The fight against foreign espionage is not just a matter for MI5. We also work closely with the Secret Intelligence Service (SIS), Government Communications Headquarters (GCHQ), other government departments, the police where appropriate, and other security and intelligence organisations in the UK and overseas.
For more information on MI5's work in countering the threat posed by foreign intelligence officers over the years, see our History section or the authorised history of MI5, The Defence of the Realm.