...and the war machine
AH-64 Apache
The AH-64 Apache is the US's key attack helicopter. First flown in 1975, the two- crew aircraft is heavily armoured to withstand close-range firing and can be used in day or night combat.
It is designed to quickly enter an enemy area and hit targets at close range before escaping to safety at a maximum speed of 225 mph (362 kph).
The Apache carries a range of armaments to hit different targets. It can carry up to 16 Hellfire missiles that can lock on to targets such as tanks from up to 5 miles (8km) away.
In closer combat, the crew turn to rockets and 1,200 rounds of ammunition in a 30mm automatic cannon.
Pilots use standard video pictures, enhanced video images and thermal imagery to identify targets - though the US military recognises that there are limitations to the thermal identification system.
The new version of the Apache, known as the Longbow, comes with a fourth system - a fire control radar system (the large bobble above the rotor blades).
This is designed to improve the crews ability to identify targets and overcome firing limitations caused by adverse weather conditions or other factors.
It also carries computers that share battlefield information with other attack aircraft and commanders at base.
The Apache played a major role in Operation Desert Storm in 1991 during which it destroyed more than 500 Iraqi army tanks along with hundreds of trucks and other vehicles.
AH-64 Apache:
Crew: Two
Main weapon: Hellfire anti-tank missiles
Max speed: 225 mph (362 kmh)
Length: 17.73m (58.2 feet)
Width: 14.3m (46.9 feet)
Weight: 9,525kg
Range: 299 miles (480km)
M1 Abrams
The main battle tank of the US Army is the M1 Abrams. Since the first M1 tanks entered service in 1980, they have been constantly upgraded, with the final version, the MIA2 boasting a larger gun, better armour and improved computer systems.
Named after General Creighton W Abrams, a former Army Chief of Staff , the M1 is America's key weapon for use in land warfare.
Its roles include spearheading assaults as well as repelling enemy forces.
Initially designed as a response to the tanks of the Soviet Union, the M1 was first used in a major conflict during the 1991 Gulf War, where it out performed Iraqi tanks, and although several Abrams were hit not a single tank crew member was killed.
Nearly 2000 were deployed during the conflict.
As well as being the backbone of the US Army and the US Marine Corps the M1 is also used by Kuwait and Saudi Arabia.
The MIA2, has a four man crew, and its 120mm gun is capable of firing six rounds a minute. Three machine guns are mounted on the tank, as are smoke grenade launchers.
It also has a stabilising system which enables the tank to fire accurately while moving.
Cooling system:
The tank's turret can turn through 360 degrees. It is well armoured, some of the Abrams use depleted uranium to increase their protection, and it has a Nuclear, Biological and Chemical attack (NBC) protection system for the crew.
The crew are stationed in a separate compartment from the fuel tanks and ammunition to increase their survival rates should the tank be hit.
The crew is made up of a driver, gunner, loader and commander.
The tank also has a sophisticated air-cooling system to keep the crew and computer systems cool during battle.
Despite its weight the Abrams can reach speeds of over 40 mph (64 km/h).
M1A2 Abrams main battle tank
Crew: 4
Main weapon: 120mm M256 smooth bore cannon
Other weapons: 1x 50 Cal M2 machinegun 2x 7.62 M240 machinegun
Max speed: 42 mph (68 kph)
Length: 9.7m (31.82 ft)
Width: 3.6m (11.81 ft)
Weight: 54,545 kg
Armour: Classified
Challenger II
The Challenger II is the UK's main battle tank, and as such its key function is to destroy enemy tanks.
It has a good reputation for reliability, although it has experienced significant problems during military exercises in desert conditions.
Improvements to air filters have had to be undertaken to enable the tank to function properly in hot and sandy environments.
Built by Vickers Defence Systems, work started on the Challenger II in 1986 and the first units were delivered in 1994.
The new model has 150 improvements over its predecessor, the Challenger I, which saw action in the Gulf War.
The UK has just under 400 Challenger IIs, some of which have been used in Bosnia and Kosovo.
The tank has a four man crew and an ability to target and destroy as many as eight targets a minute. Its fire control system is computerised and both the commander and gunner can locate enemy targets.
Speed:
Its main weapon is a 120mm gun, which is capable of firing depleted uranium rounds.
It also uses armour piercing fin-stabilised discarding sabot (APFSDS) and high explosive squash head (HESH) shells.
The tank carries two machine guns, one for anti-aircraft fire and a second for attacking enemy troops. It also has smoke grenades.
In addition to its Advanced Armour Technology the Challenger 2 also has a nuclear, chemical and biological attack resistant compartment for the crew.
As long as they have rations the crew should be able to remain in the tank for the duration of any chemical attack.
The crew compartment has an air filtering system, as well as a heating and cooling system, it is also separated from ammunition for increased safety.
The Challenger II is powered by a Perkins 26.1 litre turbocharged diesel engine, CV12. This gives the Challenger an average cross country speed of 24 miles per hour (40 kph).
Iraqi tanks
Military analysts say Iraq has a relatively poor tank capability compared with the US and British forces it might face in any ground attack.
It probably had more than 5,000 main battle tanks prior to the last Gulf War - and about half that number once the coalition had finished pounding them, though estimates vary.
Anthony Cordesman of the Centre for Strategic and International Studies, in Washington DC, says there are currently about 700 fairly modern Soviet-built T- 72s.
He estimates another 600 to 700 old American or European-built M-48s, M-60s, AMX-30s, Centurions and Chieftains captured from Iran or obtained in small numbers from other countries.
There could be another 1,000 or so obsolete tanks of Soviet and Chinese manufacture, on which Iraq might have upgraded the guns and armour.
The T-72s are easily the most capable and experts say these are the preserve of the elite Republican Guard.
Spares production:
A Soviet-supplied factory was established in the 1980s to build Iraq's own version of the T-72, known as the "Lion of Babylon".
According to Jane's Intelligence Review, the factory produced few complete tanks but in the mid-1990s was making enough spare parts to keep remaining Iraqi T-72s running.
The head of the US joint chiefs of staff, General Richard Myers, told the House of Representatives in September 2002: "Despite the presence of UN sanctions, Iraq has repaired and sustained key elements of its offensive, conventional forces."
He said Iraq maintained "more than 2,000" main battle tanks.
The T-72 has a 125mm main gun, 7.62mm machine gun and 12.7mm air defence machine gun mounted on the commander's cupola.
Later versions have a laser range-finding gun sight, ballistic computer and stabilisation so that they can fire accurately while moving.
Unequal:
Ammunition includes armour-piercing, high-explosive anti-tank and fragmentation rounds.
But the Iraqi tanks proved no match for earlier versions of the American M1 during the last Gulf War.
A T-72 has an effective range of about 1,800 metres, while the range of a US M1 Abrams is nearly twice that - although if stationary the T-72 can also fire anti- tank, laser-guided missiles to about 4,000 metres.
Anthony Cordesman says M1s - and British Challenger tanks - have better armour, are easier to drive and shoot with, and have far better control and communications equipment.
What is more, in any new conflict they would again probably have a monopoly of support from jet fighters and helicopters, he said.
Moab
The Moab is an American experimental precision-guided bomb weighing about 21,000lbs (9,525kgs) - the largest non-nuclear weapon there is.
The Moab is an Air Force Research Laboratory technology project due to be completed in October 2003.
It is a modernisation of the current biggest bomb, the BLU-82B Commando Vault or "Daisy Cutter".
That is a 15,000lb device first used in Vietnam. Most recently a handful were used in Afghanistan.
It is so big it can be "launched" only by pushing it out of the open back door of a C-130 type transport plane on a sled, which falls away.
The new bomb was tested in the same way but differs significantly in having satellite and inertial guidance.
Whereas the Commando Vault simply falls to earth under a stabilising parachute, the new weapon directs itself towards the target and could be dropped from a higher altitude.
It contains a larger amount of the same explosive slurry of ammonium nitrate and powdered aluminium.
Moab stands for Massive Ordnance Air Blast - it is detonated above ground for maximum impact over a wide area.
Psychological warfare :
These huge bombs create such massive explosions that one of the reasons for using them - or threatening to - is psychological.
This might be the key to the timing of the latest Moab test, and it is not clear how soon the experimental weapon might join the military arsenal.
The acronym Moab was already in the US military lexicon, standing for Missile Optimized Anti- Ballistic, according to the Ballistic Missile Defence Organization glossary.
To some the re-use of the name for a high-profile big bomb seems a little contrived - the acronym rather neatly lending itself to the "unofficial" nickname, Mother Of All Bombs.
Saddam Hussein said before the 1991 Gulf War that it would be the "mother of all battles".
The name has upset some.
The mayor of Moab, Utah - population 5,000 - wrote to the US president in February 2003 asking for another name to be used, fearing it would damage the town's image as a rural idyll famous for its outdoor pursuits.
The biggest bomb that has been used in aerial warfare was the 22,000lb British World War II Grand Slam, designed by Barnes Wallis.
The American B-36 bomber of the 1950s tested - but never dropped in anger - the 43,600lb T- 12 bomb.
Iraq's air defences
Iraq's early warning and air defence systems have been ground down by a dozen years of air attacks by coalition forces.
Yet the attacks keep happening - and were intensified before the invasion - because Iraq keeps on repairing what its official news agency calls the "heroic missile forces and brave ground-to-air defences".
The Iraqis routinely fire surface-to-air missiles and artillery at American and British warplanes patrolling the so-called "no-fly zones" over northern and Southern Iraq.
American officials have said there were almost 500 such attacks during 2002.
The Iraqis have never managed to hit coalition fighter jets, although in July 2001 the pilot of an American U-2 spy plane reported feeling the shock wave from an exploding missile while flying over southern Iraq.
This was regarded as significant because the U-2 flies at very high altitude.
Iraqi analyst Dr Mustafa Alani, of the London-based Royal United Services Institute, said this might suggest a relatively sophisticated system.
"Either the system was very effective - or it was just by luck, because it hasn't happened again."
Iraq did bring down an unmanned US Predator reconnaissance plane in 2001 - claiming this was as a result of having upgraded its defences.
It is also reported to have downed three unmanned Iranian reconnaissance craft being used to look for Mujahideen Khalq rebel bases inside Iraq.
According to the military think tank GlobalSecurity.org in Washington DC, Iraq has perhaps 2,000 surface-to-air missiles (SAM) of different types, as well as thousands of anti-aircraft guns.
Residential sites :
But the missiles are mostly "antiques" according to Dr Alani.
He said the original four-sector air defence system, controlled from Baghdad, was largely obliterated during the last Gulf War, and essentially only the central sector around the capital remained.
He said anti-aircraft artillery and SAM sites had been situated in residential parts of the city, making them difficult to hit from the air without causing civilian casualties.
The Iraqis have also been inventive in adapting what they have.
Images released by the US Department of Defence have shown Soviet-made S-125 SAMs, originally made for fixed launchers, mounted in pairs on the back of a truck - and being fired at coalition aircraft in southern Iraq.
Iraq's repairs to its overall control system are said to have included the installation of fibre optic communication cables.
These were allegedly of Chinese origin - though both China and Iraq denied press reports to that effect.
British defence sources have also said that Serbia, under the former President Milosevic, helped to rebuild underground air defence facilities in Iraq.
Capability:
Last year US Air Force general John W Rosa told journalists: "The Iraqi air defence system is one of the toughest, most complex systems that we see in the world. "It's very capable. They're constantly working to improve it, and they have been."
He declined to characterise its current capability.
"It's bad," according to Andrew Brookes, an air specialist at the International Institute for Strategic Studies in London.
And whatever was left would be "hit with a vengeance" within 30 minutes of any attack on Iraq starting, he said.
"All the aircrew who are out there have been practising in that region for years - it'll be like going back to training."
Source: Jane's Intelligence Review
