The newly revealed exploits of spies who operated in underground tunnels The CIA dug a tunnel under the Kremlin and installed a hi-tech bugging system to eavesdrop on the Soviet Union's most senior figures, according to the former US intelligence officer who executed the plan. The device was put in by a US agent who had to wear a protective suit and was guided by satellite and sonar images of Moscow's underground. The bugging formed part of audacious operations to rescue a key defector, a KGB officer with responsibility for eavesdropping, and to alert Boris Yeltsin to the attempted coup...