After two decades of development, India's DRDO (Defense Research and Development Organization) has completed work on the Nag ("Cobra") anti-tank guided missile (ATGM). The 93 pound missile has a 18 pound warhead and is "fire and forget" (the operator gets the target in the cross hairs, and fires the missile that will remember where the target is.) The Nag moves at 230 meters a second for up to 6,000 meters (8,000 if air launched.) The Nag is a top attack missile, that detonates its tandem (to defeat reactive armor) warhead when above the vehicle, and thus easily penetrates the thinner top armor. The Indian Army is buying 4,000, and an air-launched (from aircraft or helicopter) version is being developed. The Nag is very similar to the U.S. Hellfire. Nag will mainly be mounted on armored vehicles (two, four missile, launchers). The missile is really too heavy to be used by infantry, while the Milan is light enough.
Nag is said to be replacing Milan ATGMs, but it really isn't a Milan replacement. India ordered another 4,100 Milans earlier this year, and some 30,000 of these have already been produced in India, under license from European firm MBDA, over the past 30 years. They have also produced nearly 3,000 launchers.
The basic Milan is a 1.2 meter long, 125mm, 7.1 kg (16 pound) missile. It has a minimum range of 400 meters, and maximum range of 2,000 meters. At max range, the missile takes about 13 seconds to reach its target. The missile is guided to the target by the operator via a thin wire. The launcher weighs 21 kg (46 pounds). The missile can penetrate about a meter of armor, making it effective against all but the most modern tanks (M-1, Challenger, Leopard II). The wire guided missile concept was developed by the Germans during World War II, for use against American bombers. The Indians pay about $30,000 per Milan missile, and have had good success with them in combat. Since the 1970s, over 350,000 Milan missiles, and 30,000 launchers have been built worldwide. More modern ATGM are wireless and require much less effort on the part of the operator, but they are more expensive.
A replacement for Milan would be something like the U.S. Javelin ATGM (anti-tank guided missile), that was introduced in 2002. The Javelin weighs 49 pounds (with disposable launch tube and battery/seeker coolant unit) and is fired from a 14 pound CLU (command launch unit). The CLU contains a 4x day sight and a 9x heat sensing night sight. The missile has a tandem (two warheads, to blast through reactive armor) that can hit a target straight on, or from the top. This latter capability enables the Javelin to destroy any existing tank (including the U.S. M1) with its 18 pound warhead. Maximum range is 2500 meters. Best of all, the seeker on the missile is "fire and forget." That is, once the operator gets the target in the CLU crosshairs and fires the missile, the computer and seeker in the missile warhead memorizes the target and homes in on it. The infantry love this, because it allows them to take cover once the missile is fired.
Since ATGMs first saw action three decades ago, operators quickly discovered that in the time it took (up to 15 seconds) for the missile to reach its target, enemy troops would often shower them with machine-gun fire. Another Javelin feature is "soft launch", where the missile is popped out of the launch tube by a small explosive charge, small enough to allow the Javelin to be fired from inside a building. Once the missile is about eight meters out, the main rocket motor ignites. The minimum range is, however, is 75 meters. It takes about 20 seconds to reload a CLU after a missile has been fired.
India's state run DRDO is a network of 51 weapons and technology laboratories, employing over 30,000 people (20 percent of them scientists and engineers.) DRDO has been late in completing weapons development programs for half a century. Efforts to shape up DRDO have consistently failed. It's all about politics (DRDO provides jobs for well connected people) and nationalism (India wants to produce its own high tech weapons.) DRDO has failed in most all areas (small arms, tanks, missiles and warplanes). The failures have grown over the years, and created louder calls for reforms.
DRDO has had some successes, which it publicizes as energetically as it can. It tries to play down the failures, or simply tout them as partial successes. But compared to defense industries in other nations, DRDO is an underperformer, and highly resistant to reform.
Nag was threatened with cancellation several times, but DRDO finally got it right. However, Nag is basically a Hellfire clone. But the U.S. Hellfire entered service 25 years ago. To the DRDO, this is not a problem. That's because DRDO is part of an effort to create a world class arms industry. To do that, you sometimes have to reinvent the wheel while you are catching up to the front runners.