When it comes to the field of intelligence gathering and interpretation, no country has older active agencies than those to be found in Britain. Britain has faced numerous conflicts over the last hundred years, from fighting the Allies in the First and Second World Wars to dealing with internal issues caused by the IRA, and in most cases it has emerged victorious and much of the credit can be given to its intelligence services. Since 1909, Military Intelligence Section Five (MI5) has operated in Britain collecting domestic intelligence information. "Officially" since 1994, the Secret Intelligence Service (SIS or MI6) has been working on foreign soil to gather information. The other agency, similar to the National Security Agency (NSA) of the United States, is the Government Communication Headquarters (GCHQ), which collects Signal Intelligence (SIGINT). MI5, based at Thames House in London, is the British security service for counter-espionage and counter-terrorism. Since 1909, MI5 has been responsible for uncovering and countering secretly organized threats to Britain's national security. MI5 also assists Britain's National Crime Investigation Service (NCIS) in major and serious criminal investigations. MI5 also collaborates with other British intelligence services by providing support when a specific person or specific group has crossed Britain's borders. MI5 is headed by a Director General and MI5 is organized into seven different branches and each has a specific area of ​​interest ranging from simple homegrown terrorism to attempted proliferation of weapons of mass destruction. Most of MI5's resources are focused on international counter-terrorism and most of... middle of paper... other small intelligence agencies, but none are as important as the main three working together on threats to the UK . national security, the Secret Service (MI5), the Secret Intelligence Agency (SIS, MI6) and the Government Communications Headquarters (GCHQ). Works Cited Aftergood, Steven. "Secret Intelligence". Intelligence agency. FAS, October 2011. Web. May 22, 2011. "Oleg Gordievsky." Wikipedia. Wiki, 21 May 2011. Web. 24 May 2011. .UK. GCHQ. London:, 2011. Web. 25 May 2011. .United Kingdom. Secret intelligence service. London:, 2011. Web. 22 May 2011. .United Kingdom. Secret services. London:, 2011. Web. 23 May 2011. .