The GRU is Russia's largest foreign intelligence agency. In 1997 it deployed six times as many agents in foreign countries as the SVR, the successor of the KGB's foreign operations directorate (PGU KGB). It also commanded 25,000 Spetsnaz troops in 1997.
The first body for military intelligence was established in 1810 by the War minister Michael Andreas Barclay de Tolly who suggested to the Tsar to create a permanent body for Strategic military intelligence.
In January 1810, The Expedition for Secret Affairs under the War Ministry was formed. Two years later it was renamed the Special Bureau.
In 1815, the bureau became the First Department under the General Chief of Staff. In 1836 the intelligence functions were transferred to the Second Department under the General Chief of Staff. After many name changes through the years, in April 1906 the Military intelligence was carried out by the Fifth Department under the General Chief of Staff of the War Ministry.
In November 5, 1918, Imperial Military intelligence was replaced by Main Intelligence Directorate of the Soviet Union. In May 1992, GRU was dissolved and became part of the new Russian Ministry of Defense.