upper turret armour and even basic weapons like Molotov cocktails, if aimed at the engine air intakes, can disable a tank. Because of these limits, tanks are difficult to use in city conflicts where civilians or friendly forces might be nearby, since their firepower can't be used effectively. Airborne threats Tanks and other armoured vehicles are vulnerable to attack from the air for several reasons. One is that they are easily detectable—the metal they are made of shows up well on radar, and is especially obvious if they are moving in formation. A moving tank also produces a lot of heat, noise and dust. The heat makes seeing them on a forward-looking infra-red system easy and the dust is a good visual clue during the day. The other major reason is that most armoured vehicles have thinner armour on the roof of the turret and on the engine deck, so an anti-tank guided missile (from an attack helicopter or ground-attack jet) hitting them from the top can be deadly even if it has a small warhead. Even a small automatic cannon is powerful enough to penetrate the rear and top sections of the engine compartment of a tank. Certain aircraft have been developed to attack armoured vehicles. Most notable is the purpose-built Fairchild-Republic A-10 Thunderbolt II, also known as the "Warthog". Although able to carry a number of different missiles and bombs (including anti-tank ordnance such as the AGM-65 Maverick), the A-10's main weapon is a 30 mm GAU-8/A Avenger Gatling gun which is capable of firing 3,900 depleted uranium armour-piercing rounds per minute. The Russian equivalent is the SU-25. Similarly, a number of helicopter gunships have been designed mainly to engage enemy armoured vehicles. The AH-1Z Viper, AH-64 Apache, HAL Light Combat Helicopter, Denel Rooivalk, Eurocopter Tiger, Ka-50 Black Shark, Mi-28 Havoc, A129 Mangusta and Westland Lynx are examples. Helicopters are very effective against armoured vehicles for many reasons. The AH-64D Longbow Apache, for example, is equipped with an improved sensor suite and weapon systems and the AN/APG-78 Longbow Fire Control Radar dome installed over the main rotor. Airborne threats can be countered in several ways. One is air supremacy. This is what the United States relies on most, which is demonstrated by their distinct lack of effective short-range, mobile air defence vehicles to accompany armoured units. Most other countries accompany their armoured forces with highly mobile self-propelled anti-aircraft