The Nag missile (IAST: Nāga; en: Cobra) also called Prospina for the land attack version is an Indian third generation all weather fire-and-forget, lock-on after launch anti-tank guided missile (ATGM) with an operational range of 500m-20km, single-shot hit probability of 0.9^[8] and 10 years of maintenance free shelf-life.^[9] It comes in five variants which are under-development namely - (a) Land version (for mast mounted system), (b) HeliNa (Helicopter-launched Nag), (c) Man portable (MPATGM), (d) Air-launched version (for air interdiction which will replace imaging infra-red (IIR) to millimetric-wave (mmW) active radar homing seeker.^[10] and (e) NAMICA (Nag Missile Carrier) tank buster which is a modified BMP-2 Infantry Fighting Vehicle (IFV) produced under licensed in India by Ordnance Factory Medak (OFMK).^[11][12][13] Nag is under the Integrated Guided Missile Development Program (IGMDP) run by Defence Research and Development Organisation (DRDO) and is manufactured by Bharat Dynamics Limited (BDL).^[14] The Ministry of Defence (MoD) announced on 19 July 2019 that the missile is ready to enter series production.^[15]

Development of the Nag missile began in 1988^[16] under A. P. J. Abdul Kalam.^[17] The first tests were in November 1990.^[16] Development was delayed for several years because of issues with the IIR seeker guidance system.^[16] The Nag missile underwent successful tests on September 1997 and 20 January 2000.^[16] In 2000, MoD announced that the Nag was likely to enter full-scale production in early 2001.^[16]

Nag was successfully test-fired for a second consecutive day on 8 August 2008, from the Test Range at Pokhran, Rajasthan, marking the completion of the developmental tests. The DRDO and Indian Army was planning to hold the user trials shortly.^[18] These will be the final trials to decide the induction of the system.^[19] NAMICA successfully completed its amphibious trials in the Indira Gandhi Canal at Rajasthan on 8 August 2008.^[20]

In 2008, Indian Army placed an order for 443 Nag missiles and 13 NAMICA carriers to be delivered within the next three years.^[21] Nag will be the first ATGM of its type that will be inducted into the army by November–December 2009. The Army urgently needed the more advanced Nag to improve kill-probability as the missile is using a tandem-charge high-explosive warhead to penetrate the armor of modern tanks.^[18] By year 2008 the development cost was ₹300 crore (US$43.4 million).^[21]

As part of the winter trial of the final-user trials, the Nag missile tested successfully by the Indian Army on 26 December 2008. During the winter trials the Nag missile zeroed in on the precise location of the target tank at a distance of 3.3 km, as required by the Indian Army. The Indian Army was also extremely satisfied with the performance of the warhead of the missile.^[22] The test conducted on 28 December 2008 was successfully completed by the Indian Army. During the test a moving target at 1.8 km was targeted in the top attack mode and a stationary target at a distance of 3.1 km. The two targets were completely destroyed.^[23] A total of five missiles were fired during day and night against stationary and moving targets. Before the induction of the missile into service, summer trials were carried out in June 2009.^[24] In July 2009 the Nag ATGM was cleared for production.^[25]

On 20 January 2010, field tests of the Nag’s Thermal Sight system saw the system identify and lock on to a T-55 tank at a range of 5 km. The trials of the missile were conducted using an advanced-imaging infrared-seeker head, as per the Army's requirements. The tank was then engaged and destroyed at a range of over 4 km [12] thus the missile’s fire-and-forget capability has been established using the day-version of the IIR passive seeker. In IIR form the Nag has limited all weather capability. This has given added impetus to develop the mmW active seeker. Efforts are on to provide special embedded on-board hunters, that can hunt for targets using ‘day seekers’ and ‘day-&-night seekers’. During trials in June 2010, the short-range capability of the missile to hit targets was validated. The Nag missile hit a target at a range of half a kilometers in just three seconds.^[26] In the follow-on test a moving target was hit within 3.2 seconds after launch.^[27] The final-user trials were held during July 2010 and successfully completed. The missile has been cleared for mass production. BDL plans to produce 100 Nag annually to replace the existing licensed produced Konkours and Milan second-generation missiles in the armoury.^[28] Nag was test-fired as part of user validation trials on 16 July 2010.^[29]

Nag has successfully completed its final-validation trials and is expected to join the Indian Army in 2011. Two missiles were launched against a moving target at a time another two missiles were launched against a stationary Vijayanta tank in quick succession and successfully hit the targets. The Indian Army was happy with the performance and is expected to buy 443 missiles for ₹3.35 billion (US$48.5 million).^[28] 450 Nag missiles along with 13 NAMICA carriers were planned to be inducted into the Army's arsenal by 2011 with the successful completion of final-validation trials in Rajasthan but this may now take some more time after the missile's failure in the user-validation trials.^[30] In 2011, the project suffered a one-year delay due to the army changing its requirements with the carrier of the missile (NaMiCa) at the last moment.^[31]

The missile tested during the summer in Rajasthan failed to achieve its objective of hitting the target at the intended 4 km range. The scientists found the fault with the heat-seeker unable to distinguish the heat signature of the target and its surroundings during extreme temperate at great distance. This led to the development of a better seeker with higher resolution and sensitivity by Research Centre Imarat (RCI), that can track and distinguish targets at long distances. The first trials of the new seeker were carried out on 29 July 2013 in the hot-desert conditions in Rajasthan.^[32] The evaluation trials carried out in September/August 2013 with the improved seeker provided fairly accurate results. Performance trials were expected to begin in early 2014.^[33]

Nag, scored a “bull’s eye” and successfully hit the target 4 km away during a night trial in the Mahajan Field Firing Range, Rajasthan in Jan 2016. During the test, the Thermal Target System (TTS) developed by a DRDO laboratory at Jodhpur was used as target for the missile and is in the final-user configuration. TTS simulated a target similar to an operational tank as thermal mapping from tank to TTS was carried out by generating a thermal signature. The trial validated the enhanced 4-km range capability of IIR seeker which guides the missile to the target after its launch. Nag cleared final developmental trials held by Indian Army in the month of September 2016, making way for the indigenous Anti-tank weapon system to enter mass production.^[34][35]

The missile was tested successfully in 5 June 2017 at its maximum range of 4 km in hot-desert conditions in a daytime trial at the Chandan Field Firing Range near Jaisalmer, Rajasthan, with a successful follow-up test taking place on 13 June 2017. DRDO shared that the trials which concluded were successful for the extreme-heat daytime conditions of the desert.^[36]

On 8 September 2017, MoD announced that DRDO has twice successfully flight-tested the missile against two different targets in two tests in the ranges of Rajasthan. The missile has successfully hit both the targets under different ranges and conditions with very high accuracy as desired by the Armed Forces. With these two successful flight trials, and the flight test conducted earlier in peak of summer, the complete functionality of Nag ATGM along with launcher system NAMICA has been established and marked the successful completion of development trials of Nag Missile.^[37] In 2017, the Army said that the developmental trials of Nag carried out earlier have only proven partial success and many more user trials will be needed."^[38] In 2017, the DRDO claimed that the Nag missile would be ready within four years.^[39]

The developmental trials of the missile were completed and it was declared ready for induction on 28 February 2018, with two tanks destroyed in desert conditions.^[40][41][42] In 2018 the single-shot hit probability was 0.77 (later improved to 0.90).^[43] In 2018, DRDO chief claimed the Nag system would be inducted into the Indian Army by 2019.^[44] On 7 July 2019, the DRDO carried out three successful trials of the Nag missile in the Pokhran firing range. The missiles were tested during both day and night. The missile is reportedly in the final stages of being inducted.^[45] The Nag missile was successfully tested 12 times between 7-18 July 2019.^[46] It was tested under extreme weather conditions during day and night, in indirect attack mode as well as in top attack mode and achieved a direct hit on the target. These trials completed the summer user trials and the missile will now proceed towards induction into the Indian Army.^[47] The missile will enter series production by the end of 2019, according to a senior DRDO official.^[48]

Nag is completely made up of fibreglass structure.^[49][50] It is developed for engaging heavily armored tanks in all weather conditions during day and night with a minimum range of 500m and maximum range of 4 km for the land variant. The third-generation fire-and-forget-class ATGM uses an imaging infrared (IIR) seeker that locks on to the target before launch.^[47] The air-frame is made up of composite materials with high resistance to enemy countermeasures. The forward dome houses the guidance system. The middle portion of the body accommodate sensor packages and the warhead. A booster rocket is located towards the rear end. NAG consists of four foldable wings and four tail fins that are fitted to stabilize it during flight operation. An image processor acting real-time next to the guidance package helps give automatic target detection and tracking capability. The digital autopilot helps in the guidance, stability and control after launch. An electric actuation system also helps in flight control. The guidance system is based on an imaging infrared (IIR) seeker that ensures a high target accuracy in both top and front attack modes. A CCD camera integrated into the guidance system is useful as it is hard to jam. The initial guidance is by area correlation around the target which later add centroid tracking mechanism. Homing at terminal phase is done by area correlation around the centroid. It rises upwards suddenly to bend at a steep angle to hit the target.^[51]

As of 2017, the Nag missile's only operational launch platform is the purpose-built NAMICA missile carrier.^[38] A number of other variants are in various stages of development.

The NAMICA (Nag Missile Carrier) is a stretched license-built BMP-2 with additional wheels named "Sarath" in India.^[16] It is classified as a tank destroyer. It is equipped with various electro-optical systems like Thermal imager (TI), Charge-coupled device (CCD) and Laser rangefinder (LRF) for target acquisition. NAMICA carries a total of twelve missiles with eight in ready-to-fire mode and four additional in storage.^[16][52] It has compact Auxiliary Power Unit (APU) for Silent Watch Operation, Fire Detection and Suppression System (FDSS) and Nuclear Biological Chemical Protection System (NBCPS). The carrier weights 14.5 tonnes in full combat load and is capable of moving 7 km/h in water. The carrier was put through transportation trials covering 155 km during 2008 summer trials.^[52] It has various modes of firing including top attack and indirect attack mode.^[47] It has a lock-on before launch system where the target is identified and designated before the launch. The range of attack is limited due to targeting system based on visual identification.

HeliNa, (Helicopter-launched Nag) is air launched version of Nag with extended range. It is launched from twin-tube stub wing-mounted launchers configuration on board HAL Rudra and HAL Light Combat Helicopter manufactured by Hindustan Aeronautics Limited (HAL).^[53] It is structurally different from Nag and is guided by an infrared imaging seeker (IIR) operating in the lock-on before-launch mode for target engagement.^[54]

The first ground launch of the missile to check Lock-on after launch (LOAL) capability were conducted in 2011 during which the missile was locked onto a target and launched. While the missile was in flight, a second target was chosen for the missile to hit which got destroyed. This demonstrated the capability of the missile to lock onto and hit another target while in mid-flight. A two-way radio frequency command-video data link has been released which is intended to be fired from HAL Rudra.^[55]

Here the missile was launched in the general direction of the target. On approaching the target, images of the area ahead are sent to the operator who will be able to identify enemy location. The command to lock on to a particular target is then updated onto the seeker after which the missile homes around the target and destroys it.^[5] It supports both top attack and direct attack functionality.^[56]

On July 13, 2015, three round trials of HeliNa were conducted by HAL at Chandhan firing range in Jaisalmer, Rajasthan. As per the defense source the missile was test fired from HAL Rudra and two missiles succeeded in hitting the targets at a range of 7 km, while one reportedly missed the target.^[57]

After successful image capturing trials in Bangalore, DRDO wants to test HeliNa with an updated 640x512 instead of 128x128 resolution IIR seeker on September 2016 for the Army Aviation Corps under hot desert conditions with moving and static targets for different range parameters.^[58]

On 19 August 2018, HeliNa was successfully test-fired from a HAL LCH at Pokhran test range.^[59]

In November 2018, an upgraded version of HeliNa, denoted Standoff Anti-tank guided missile (SANT), was successfully tested at Pokhran.^[60] The upgraded version of missile is equipped with a new nose-mounted active radar seeker and has a range of 15-20 km.^[61]

DRDO and Indian Army tested HeliNa with a range of 7-8km from Integrated Test Range (ITR) in Chandipur, Odisha on February 8, 2019 to check the maximum missile range and accuracy.^[62]

The Man Portable Anti-tank Guided Missile (MP-ATGM) is an Indian third-generation Anti-tank guided missile derived from the Nag missile.^[63]