| ROKS-2 flamethrower | |
|---|---|
A captured ROKS-2 flamethrower at the Mikkeli Infantry museum, Finland (2011) | |
| Type | Flamethrower |
| Place of origin | Soviet Union |
| Service history | |
| In service | 1935−1945 (USSR) |
| Used by | Soviet Union |
| Wars | Second World War, Vietnam War |
| Production history | |
| Manufacturer | Different manufacturers |
| Produced | 1935-1941 |
| Specifications | |
| Mass | 22.7 kg (50.0 lb) |
| Crew | 1 |
| Effective firing range | 25 m (27 yd) |
| Maximum firing range | 45 m (49 yd) |
| Feed system | 9 L (2.4 US gal) fuel tank 1 nitrogen tank (propellant) |
| Sights | None |
The ROKS-2 and ROKS-3 (Shortened from Russian, Rantseviy Ognemyot Kluyeva-Sergeyeva; Ранцевый Огнемёт Клюева — Сергеева; "Kluyev-Sergeyev backpack flamethrower") were man-portable flamethrowers used by the USSR in the Second World War.
The ROKS-2 was designed not to draw attention, so the fuel and gas tanks were concealed under a sheet-metal outer casting resembling a knapsack; the flame projector was designed to resemble a standard Mosin–Nagant rifle. Operators of flamethrowers during The Great War were immediately targeted, so by camouflaging it to look like a rifle the ROKS-2 protected the operator from being specifically targeted by the enemy.
ROKS-2 had two vertical fuel tanks connected by pipe to a horizontal pressurized nitrogen tank. The nitrogen tank was pressurized at approximately 113 bars (11,300 kPa) and used a propellant for the fuel. The flame shots were ignited by firing specially modified 7.62×25mm Tokarev cartridges.
The ROKS-2 was used, amongst other engagements, during the close-range fighting during the first days of the Battle of Kursk in 1943.
The Finnish designation for captured ROKS-2 units was liekinheitin M/41-r. Captured Soviet flamethrowers saw some use by Finnish forces during the Continuation War. They were operated by two-man teams of combat engineers. They were well regarded by the Finns, although flamethrowers of all kinds saw little use by Finnish forces.
During the German invasion of the Soviet Union in 1941, production in factories struggled to keep up with the demand for weapons, including production of the ROKS-2. This led to the creation of the ROKS-3. The ROKS-3 was a simplified model designed to be easier to manufacture. It did away with the disguise for the backpack, though it retained the flame projector designed to resemble a rifle. Both models carried around 9 litres (2.4 US gal) of fuel. The fuel was propelled by nitrogen gas pressurized at 115 bars (11,500 kPa) and, under ideal circumstances, had a maximum range of around 45 metres (49 yd).

Some ROKS-3 units were supplied to North Korea, Czechoslovakia, Kingdom of Yemen (via Czechoslovakia), and North Vietnam.