January 17, 2008: JDAM (GPS satellite guided bombs) were developed in the 1990s, shortly after the GPS network went live. These weapons entered service in time for the 1999 Kosovo campaign, and have been so successful, that their use has actually sharply reduced the number of bombs dropped, and the number of sorties required by bombers. The air force generals are still trying to figure out where this is all going.

After the invasion of Iraq, the U.S. Air Force ordered a sharp increase in JDAM production, aiming for 5,000 JDAM a month. They ended up needing far less. In 2005, about 30,000 JDAM were ordered. That fell to 11,605 in 2006 and 10,661 in 2007. This year, only 5,000 are being ordered. Nearly all those ordered in the past few years are being put into the war reserve. Only a few thousand a year are actually being used, and this includes those expended during training.

The appearance, and impact, of JDAM has been sudden. While guided bombs first appeared towards the end of World War II, they did not really become a factor until highly accurate laser guided bombs were developed in the 1960s. A decade later, TV guided bombs came into service. But these guided bombs were expensive, costing over $100,000 per bomb. Even as late as the 1991 Gulf war, only 16 percent of the 250,000 bombs dropped were guided. But analysis of the battlefield later revealed that the guided bombs had done 75 percent of the actual damage. But the guided bombs were still too expensive, and lasers were blocked by many weather conditions (rain, mist, sand storms). Something new was needed to replace dumb bombs completely. The solution was GPS guided bombs.

In 1991, the GPS system was just coming into service. There were already plans for something like JDAM, but no one was sure that it would work. Once the engineers got onto it, it was discovered that JDAM not only worked, but cost less than half as much to build ($18,000 per bomb) as the air force expected ($40,000 a bomb). The current price is still under $30,000 each.

So in 1996, production of JDAM began. The bombs got their first workout in the 1999 Kosovo campaign. To everyone's surprise, 98 percent of the 652 JDAMs used, hit their targets. In 2001, JDAM proved the ideal weapon for supporting the few hundred Special Forces and CIA personnel the U.S. had on the ground in Afghanistan. The JDAM was more accurate, and effective, than anticipated. By January, 2002, the U.S. had dropped about half their inventory, of 10,000 JDAMs, in Afghanistan.

In 2003, 6,500 JDAM were used in the three week 2003 Iraq invasion. Since 1999, American aircraft have used less than 25,000. New versions have added more capabilities. The latest versions are even more accurate, putting half the bombs within ten meters of the aiming point. A new 250 pound version (the SDB) entered service last year. Another new version, with wings, is on the way, which will enable a bomber to drop the bomb up to 100 kilometers from the target. JDAMs are pretty rugged. F-22s have dropped half ton JDAMs, from 50,000 feet, while flying at over 1,500 kilometers an hour.

In the last decade, the appearance of so many precision weapons has changed tactics on the ground. This proliferation of precision has also changed the way smart bombs are designed. With the ability to put a weapon within a meter of the aiming point (using laser guidance) or 5-10 meters (using GPS), smaller is now better, especially in urban areas where there are a lot of civilians about. But even without civilians around, smaller, more precise bombs and missiles are preferred, as that allows friendly troops to get closer to the target, and rush in right after the explosion, to finish the job. Troops have changed the way they fight because of this. There is more movement in urban warfare because of all this precision firepower, and fewer friendly fire casualties from bombs and artillery.

But it's not just the air force and their smart bombs that have brought this on. The army had precision missiles on the ground long before JDAM came along. Thus, over the last five years, there has been a competition between the army and air force to develop smaller, cheaper and more precise, missiles and bombs.

A decade ago, there were several precision weapons to choose from, but all were very expensive. Basically, if you add high precision to a bomb or missile, you increase its cost by $25-50,000. One of the first, widely successful precision weapons to show up was the fifty pound TOW anti-tank missile. It has a 13 pound warhead, and, when wars broke out, was mainly used for taking out rooms in buildings where enemy gunmen were hiding. Every mech infantry unit has plenty of TOW missiles, and very few enemy tanks to use them on.

Sometimes too much of a good thing is bad. Although the air force had smart (GPS guided) bombs in 2001, these came in only two sizes; half ton and one ton. This was too much blast for urban fighting. The need for less firepower compelled the air force to quickly modify its GPS guidance kit to fit on a 500 pound bomb. But that's still 280 pounds of explosives. The troops wanted precision, and less bang. In response, the air force (actually, the navy) developed a 500 pound bomb with all but 30 pounds of the explosives removed. Then there's a completely new smart bomb design, the 250 pound SDB (small diameter bomb). This weapon has a shape that's more like that of a missile than a bomb (70 inches long, 190 millimeters in diameter), with the guidance system built in. The smaller blast from the SDB is still pretty substantial (51 pounds of explosives). A new SDB design has a Focused Lethality Munition (FLM) warhead, which reduces the number of metal fragments created when the bomb explodes, and increases the blast effect. This is meant to reduce casualties to nearby civilians, but it's still a bigger bang than the low-explosive 500 pound JDAM. Moreover, the low-explosive JDAM costs about half as much as the SDB. The one advantage of the SDB is that you can carry more of them, as they are much more compact than 500 pound bombs.

Since the 1990s, a more portable ground combat missile, and just as accurate as TOW, came along in the form of the 26 pound Javelin, with its nine pound warhead. These two missiles are expensive, with TOW costing $25,000 each, and Javelin $75,000. But even that can be too much bang for the infantry. That's why the AT4 rocket launcher, and its four pound warhead is so popular. It's not laser guided, and you have to be pretty close to use it. But at the normal ranges its used (a hundred meters or so), it's very accurate, and it's cheap ($2,700). The LAW is similar, smaller (2.2 pound warhead) and cheaper ($2,000).

Helicopters and UAVs use Hellfire missiles, which weigh 100 pounds, and have a 20 pound warhead. A little less than half of a missile warhead is explosives. Hellfire is laser guided, and good for taking out vehicles full of bad guys. Hellfire costs $50,000 each. For about the same price you can use the 44 pound Viper Strike, and its four pound warhead. Even cheaper ($25,000 each), and smaller, are the new, laser guided 70mm rockets. There weigh 25 pounds and have a six pound warhead. The Viper Strike is a laser guided glide bomb that basically comes straight down. The 70mm rocket has a range of about six kilometers.

The army also has 155mm GPS guided 155mm shells (Excalibur). Each hundred pound shell has about 20 pounds of explosives. This makes for a bigger bang than Hellfire or Tow, but much less than smart bombs. There's also a 227mm MLRS GPS rocket. But this carries over 150 pounds of explosives. About half the bang of a 500 pound JDAM. The GPS guided 155mm shell and MLRS rocket each cost over $50,000 each. The big advantage of these GPS artillery munitions is that they are available to the troops 24/7, and the need for fewer rounds per mission means there are fewer problems with running out, or low, on supplies.

Price is not really a factor when it comes to these weapons. The whole point of smart (much more accurate) munitions is to reduce the number of explosions, and to only blow up what needs to be destroyed. The proliferation of rockets, smart bombs and missiles, from those with a pound of explosives (LAW) to 500 pound bombs (with 280 pounds), gives troops a lot of flexibility on the battlefield. This makes American troops much more lethal, and greatly reduces friendly, and civilian, casualties.

The enemy had had a hard time adapting to smart weapons. In Afghanistan and Iraq, the enemy largely gave up trying to fight American troops head on. Ambush, roadside bombs and boobytraps became the preferred methods of attacking U.S. troops. This is a major concession by the enemy, and has been a major factor in the success of American forces since JDAM became available. You cannot win if you cannot eventually confront and defeat the enemy ground troops.

As long as the U.S. maintains air superiority, as it has since 1944, enemy forces will not benefit from the new precision bombs. They will still be able to use precision ground launched missiles and artillery shells, but that will be small consolation when your forces are being pounded by thousands of JDAMs.