Operations and reforms of Russian frogmen units:

• 1938 October 22: During a wargaming between units of the Russian Pacific Fleet in Vladivostok, a group of Soviet military divers exited an SCH-112 military submarine through a torpedo tube, entered the naval base and completed certain acts of sabotage. Those combat divers were equipped with oxygen rebreathers, dry suits, handguns and grenades. However, this did not lead to a permanent combat diver unit being set up. This is the beginning of the history of combat divers.

• 1941 August 11: RON (рота особого назначения, Rota Osobogo Naznacheniya; Company of Special Designation), a Soviet combat frogman unit, was set up on Goloday Island (which is now called Dekabristov Island) near Leningrad. Its commander was Ivan Vasilyevich Prokhvatilov.

• 1941 August: 2 RON frogmen towing a sea mine demolished a bridge over the river Narva which German forces had reached.

• 1941 September: During Finland's army's re-invasion of the area around Lake Ladoga which had been lost to the USSR, Finnish forces took an island south of Vyborg, isolating 23 Soviet units who were in Vyborg port. Two RON frogmen swam to the island, laying a guide cable. 50 RON frogmen followed this cable and landed and found that the Finns had removed parts from their guns and abandoned the island, perhaps because the Finns had seen the Soviet preparations.

• In these early days RON made its own equipment, including adapting army breathing sets for underwater use; they did not use fins until the end of the 1950's.

• 1941 September 23: 270 German aircraft attack the Soviet naval base at Kronstadt near Leningrad. During this they sank a transport vessel "Barta" opposite Peterhof. It sat on the seabed but remained partly out of the water.

• 1941 September: Prokhvatilov decides to use the Barta wreck as an observation post. They saw that the Germans had built a big pier at Staraya Peterhof, and piles of naval mines by it. RON frogmen towed two naval mines to the pier and destroyed it. The Germans did not rebuild it.

• The Germans had built V1 rocket launching pads in the Strelna area to bombard Leningrad. The diver-intelligence officer Vladimir Borisov swam to the area and changed into German clothes and reconnoitered in the plant and returned and reported what he had found. Soviet aircraft and artillery destroyed the V1 launching pads.1941, first part of October: start of frogman training in the Soviet Pacific Fleet.

• 1941-1943, winters: RON men patrol the supply road over the ice of frozen Lake Ladoga.

• 1943 September: During the long siege of Leningrad, a group of Soviet Underwater Spetsnaz troopers (combat swimmers of RON unit) entered a German naval base at Strelna and destroyed Italian combat boats of the Decima Flottiglia MAS.

• 1944 April: ROON (a unit like RON) was formed in the Soviet Black Sea fleet.

• 1944 July: Combat swimmers of RON completed underwater work onboard of the German submarine U-250, which had been sunk by a Soviet anti-submarine MO-103 Hunter-killer. Some secret documents and a new type of acoustic torpedo were found. Later some key components of this T-5 G7es torpedo were given to British naval specialists by the Soviet forces. German aircraft and torpedo boats tried to interrupt the diving operation. The negotiations between Soviet and British sides about the T-5 acoustic torpedo are depicted in the book "The Way to Victory" written by Soviet admiral N.G. Kuznetsov.

• 1945 October: RON and ROON and all similar organizations were officially disbanded.

• 1946 July; 1950 start; 1952 May 29: discussions in the USSR about need for combat frogmen.

• 1953 January 24: A conference in the USSR confirmed that combat frogmen were needed.

• 1953: The first naval combat divers' unit, the 6th OMRP, was established in the Black Sea.

• 1954: Scuba divers' or frogmen's footprints were found a beach near a sanatorium used by Soviet state party elite. This caused a security alarm and pushed the USSR towards forming a combat frogman unit.

• 1954 October 15: The naval combat divers' unit, the 561st OMRP, was established in the Baltic Sea.

• 1956 April: The Lionel Crabb underwater spying incident at the Soviet warship Ordzhonikidze caused a security alarm and pushed the USSR towards forming a combat frogman unit.

• Of Soviet oxygen rebreathers whose make codes end in two digits, the lowest such number is 51 (the IDA51). (The characteristic metal backpack-box (like the IDA71 has), seems to be first definitely known of in the LVI-57; the LVI-57 shown on Jan Willem Bech's site was made in 1964.) Sometimes with Soviet products (as with the AK47 rifle) these numbers indicate when that make came into production, e.g. the IDA71 in 1971.

• 1967 June: When the Six-Day War between Israel and Arab nations happened, some Soviet ships were in Port Said. This showed Soviet naval commanders that Soviet ships in the Eastern Mediterranean were well protected from air attack, but were not properly protected from frogman attacks. As a result, afterwards Soviet naval commanders decided to form the PDSS.

• 1967: PDSS (Противо-Диверсионные Силы и Средства, Protivo-Diversionnyye Sily i Sredstva = Anti-diversionary forces and means) started to be developed in the Soviet Black Sea Fleet. PDSS is a complex of special measures developed by the Soviet Navy to counter possible attacks by frogmen. PDSS includes special trained units (teams) of the Soviet Navy, and frogman and anti-frogman training, and special weapons and tactics. According to some historians, Soviet Naval Commanders decided to form PDSS after the Lionel Crabb incident. PDSS includes special trained units (teams) of the Soviet Navy, and special weapon and tactics.

• 1968: The 6th OMRP was transformed into the 17th Отдельная бригада специального назначения, OBrSpN, Otdel'naja brigada spetsial'nogo naznacheniya = Detached Brigade for Special Purpose).

• 1969: PDSS units were formed in the Soviet Pacific and Baltic and Northern fleets.

• 1970 and after: frogmen from the OB PDSS operated in Angola, Vietnam, Egypt, Mozambique, Nicaragua, Ethiopia, etc, often on request of the nation that they operated in. They went to Angola and Nicaragua to protect Soviet ships and to consult with local armed forces men.(date unknown): Soviet frogmen were protecting a USSR trade commission who were visiting a place on the coast of Africa, and they saw and fought against and drove off a group of 6 or 8 South African combat frogmen in an underwater fight. No deaths.

• 1989: Mihail Gorbachev and George H. W. Bush met onboard the Soviet ship Maksim Gorkiy near the coast of Malta, and for 3 days frogmen from the Baltic Fleet (including spetsnazmen from the 561 OMRP) and Osnaz protected it.

• 1990: The 17th OBrSpN was transformed into the 1464th OMRP.

• 1995, January-May: Several seamen, midshipmen, warrant officers, and officers from different OMRPs as volunteers took part in the 1st Chechen War. They were included into the Naval Infantry units, and operated as average Marines in Naval Infantry's reconnaissance units, not as a separate Spetsnaz unit.

• 2004: The Russian State-controlled Channel One showed a documentary film dedicated to some operations of Spetsnaz which were not known by the general public. The film is called "Spetsnaz: the Operations". Among other stories, the film depicted an episode about tactics of Russian combat swimmers from a PDSS unit. The episode was based on a real incident that occurred a few years earlier in a Russian naval base. Agents of a Russian PDSS team detected activity of foreign frogmen inside a naval base. According to the film's narrator, those frogmen were well-trained professionals and they planned to accomplish a terrorist action inside the Russian base as a Russian battleship was arriving in a harbour. The intruders had recruited a local man as a source of information. They planned to destroy a pier together with relatives of naval officers and sailors by remote explosion of a special mine. During fast and bloody combat all the foreign frogmen were killed, and their weaponry and explosive devices and diving equipment were captured by a PDSS team.