Operation Scherhorn (in English sources) or Operation Berezino (original Soviet codename) or Operation Beresino (in East German sources) was a secret deception operation performed by the NKVD against the Nazi secret services from August 1944 to May 1945. It was proposed by Joseph Stalin, drafted by Mikhail Maklyarsky [ru] and executed by Pavel Sudoplatov and his NKVD subordinates, assisted by German antifascists and communists.

The main objective of Operation Berezino was to create the illusion of a large German armed group operating behind the front line in Soviet held territory, and to deplete Nazi intelligence resources through capture and extermination of field operatives sent to assist these fictitious troops. The NKVD set up a fake German "resistance pocket" under "command" of Lieutenant-Colonel Heinrich Scherhorn [de; ru], a real German prisoner of war who was forced to cooperate with the Soviets. The German response, Otto Skorzeny's Operation Freischütz (Operation Poacher in post-war English sources), developed according to Soviet expectations. The German commandos sent by Skorzeny were routinely arrested and forced to take part in the Soviet funkspiel. German support gradually faded but the German command maintained radio contact with "Group Scherhorn" until May 1945.

According to Pavel Sudoplatov, NKVD officers Victor Ilyin and Mikhail Maklyarsky conceived Operation Berezino as an extension of Operation Monastyr ("Operation Monastery") (1941–1944). In 1941, NKVD operative Alexander Demyanov [ru] (Алекса́ндр Петро́вич Демья́нов, Soviet codename Heyne), who disguised himself as a disgruntled bohemian socialite, established contact with the German resident in Moscow. The NKVD used this opportunity to expose the Abwehr undercover network in the Soviet Union. In December 1941, Demyanov "defected" to the Germans and showed up at the Abwehr field office in Smolensk, a city in western Russia near the border with present-day Belarus. Three months later, he returned to Moscow as a trusted German agent. His apartment became a death trap for scores of genuine German agents, but he retained the trust of his German superiors. In the middle of 1942, Demyanov's control officer, Willie Fischer, expanded the operation into a strategic level disinformation campaign. For more than two years, Demyanov supplied Reinhard Gehlen, the head of Fremde Heere Ost (Foreign Armies East) department with carefully-scripted "military plans."

According to Sudoplatov, the German success in repelling Operation Mars was, in part, influenced by "correct" information fed to Gehlen through Demyanov. The intent of feeding the Germans information about an operation, was to conduct strategic deception to distract the Germans from the simultaneous Operation Uranus, in the south. The Germans were indeed surprised by the latter attack, which resulted in the encirclement and eventual surrender of the German 6th Army at Stalingrad. This account is disputed by historian David Glantz, who argues that the Rzhev operation was not intended as a deception or diversionary attack but that it became a post hoc propaganda justification that shielded Georgy Zhukov from blame for the costly failure of Operation Mars.

According to Sudoplatov, Joseph Stalin personally monitored the progress of Operation Monastyr. The NKVD men who engaged in it were highly rewarded, but Stalin was dissatisfied with the limited scope of the operation. Shortly before the beginning of Operation Bagration, he summoned Victor Abakumov, Vsevolod Merkulov, Fyodor Fedotovich Kuznetsov, and Sudoplatov and ordered a new disinformation campaign. Stalin's instructions, recorded by Sergei Shtemenko, shifted the objective toward methodical physical destruction of German special forces and their intelligence capability. Sudoplatov had to set up a believable "German camp" behind the advancing Soviet troops and call the German command for help. Stalin reasoned that the Germans would expend their best commandos in futile rescue missions. The fake "camp" would also divert German airlift resources from supporting the real pockets of resistance.

The new operation, codenamed Berezino, was drafted by Colonel Mikhail Maklyarsky and approved by Stalin, NKVD Chief Lavrenty Beria and Foreign Minister Vyacheslav Molotov. NKVD officers Nahum Eitingon, Willie Fischer, Mikhail Maklyarsky, Alexander Demyanov and Yakov Serebryansky departed to Belarus with a group of ethnic German antifascists. More pro-Soviet Germans, who earlier engaged in mopping up Polish and Lithuanian forest brothers, joined them at the base camp some 100 kilometres (62 mi) east of Minsk. The NKVD men screened groups of German prisoners-of-war captured during Operation Bagration and picked Lieutenant-Colonel Heinrich Scherhorn as the "front" for their operation. Scherhorn, a former commander of the guards' regiment of the 286th Security Division, was taken prisoner on July 9, 1944. According to the NKVD veteran Igor Schors, the choice was sealed by the connection between the Scherhorn family and Hitler. In the early 1930s, Scherhorn's father had made substantial donations to the Nazi Party. Scherhorn and his radio operator agreed to play the Soviet game. German communist Gustav Rebele assumed the role of Scherhorn's aide, watching his "commander" day and night.

Berezino began on August 18, 1944 with a wireless message from Max, who was actually the NKVD agent Alexander Demyanov, to German Command. Max reported that Scherhorn's detachment of 2,500 men was encircled by the Soviets in the swamps near the Berezina River. According to German sources, Colonel Hans-Heinrich Worgitzky of OKH Counter-intelligence suspected a Soviet Funkspiel and refused to commit his men to rescue "Scherhorn". Gehlen intervened and demanded full support to "Scherhorn" which he thought would ideally fit Otto Skorzeny's plan of guerilla action behind the front line. Oberkommando der Wehrmacht (OKW, High Command of the Armed Forces) Chief of Staff Alfred Jodl instructed Skorzeny to begin the rescue operation.

According to the German communist Karl Kleinjung [de], in early September, Eitingon announced the first success; the German command confirmed departure of a group of four or five commandos. The Soviets mustered a "welcome party" dressed in battered Nazi field uniforms. Some, like Kleinjung, were ethnic Germans, but others were NKVD men who did not speak the language. Between 01:00 and 02:00 on September 16, a Heinkel He 111 made two runs over the drop zone, releasing supply containers and paratroopers. According to the official site of the SVR there were three radio operators. According to Kleinjung, there were two SS commandos, with one of them a radio operator and two agents of Baltic descent. The last two were quietly subdued by NKVD, and the two SS men were cordially welcomed and escorted to Scherhorn's tent. After the meeting, the guests were arrested by the NKVD and forced to cooperate in the Funkspiel. They reported their safe landing over their wireless set, which persuaded the German command that the operation was proceeding as planned. They were followed by three more commando teams. According to Kleinjung, the NKVD intercepted all three without arousing suspicion.