India recently revealed that because it joined the MTCR (Missile Technology Control Regime) in June it could speed up the acquisition of the ten Israeli Heron TP UAVs the government agreed to purchase in September 2015. MTCR was seen as a problem because the MTCR prohibits member states from selling missiles or UAVs (or the needed tech to build them) carrying a payload of half a ton (500 kg) or more and a range exceeding 300 kilometers.
The Heron TP was not designed to carry nukes but in theory it could and thus it is a MTCR violation. Created in 1987, MTCR was one of several breakthrough arms control treaties agreed to during the 1980s. Compliance with MTCR rules is voluntary but 35 nations have signed on and pledged to abide by MTCR rules. Israel is not one of them but has promised not to export tech covered by MTCR to any country that is not a MTCR member. So India joined MTCR in order to remain on the side of the righteous.
The Heron TP is equipped to carry smart bombs and guided missiles but is used mainly for long range reconnaissance and surveillance. India is paying about $40 million each for the Heron TPs. India has been buying Israeli UAVs for over a decade. The late 2015 Indian decision to buy Heron TPs was one response to Pakistani announcing its first use (against Islamic terrorists) of an armed UAV. It is unclear who India would use an armed Heron TP against.
The Heron TP was developed as an unarmed surveillance aircraft, but there has been so much demand for armed UAVs that in 2013 Israel modified the Heron TP to handle weapons. The Heron TP entered squadron service in the Israeli Air Force (with 210 Squadron) in 2009. The UAV's first combat service was in 2010, when it was used off the coast of Gaza, keeping an eye on ships seeking to run the blockade.
Development of the Heron TP was largely completed in 2007, mainly for the export market, and the Israeli military was in no rush to buy it. There have been some export sales and the Israeli air force eventually realized that this was an ideal UAV for long range operations or for maritime patrol. But it turned out there were few missions like that.
Equipped with a powerful (1,200 horsepower) turboprop engine, the 4.6 ton Heron TP can operate at 14,500 meters (45,000 feet). That is above commercial air traffic and all the air-traffic-control regulations that discourage, and often forbid, UAVs fly at the same altitude as commercial aircraft. The Heron TP has a one ton payload, enabling it to carry sensors that can give a detailed view of what's on the ground, even from that high up. The endurance of 36 hours makes the Heron TP a competitor for the U.S. 4.7 ton MQ-9 Reaper. The big difference between the two is that Reaper was designed as a combat aircraft, operating at a lower altitude, with less endurance, and able to carry a ton of smart bombs or missiles. Heron TP was designed mainly for reconnaissance and surveillance especially since Israel wants to keep a closer, and more persistent, eye on Syria and southern Lebanon.