One of the first things the new American Secretary of Defense (a retired marine general with experience in Iraq and Afghanistan) did when he started work in early 2017 was increase planned purchases of guided bombs and missiles. Nearly $3 billion worth of these guided weapons have been used since the U.S. began its campaign against ISIL (Islamic State in Iraq and the Levant) in mid-2014. The upgraded Department of Defense munitions order comes to $16.4 billion. While 18 percent is for strategic missiles the rest is for the smart bombs, rockets and guided missiles used daily since 2001. This order includes 7,664 Hellfire missiles (at $94,000 each), 34,529 JDAM (at $26,000 each), 6,000 GMLRS (at $149,000 each), 7,312 SDB (at $69,000 each), 100 Tomahawk Missiles (at $3.9 million each) and 6,600 APKWS (at $30,000 each). For some of these weapons the number ordered is based on the current maximum monthly production which is 638 Hellfires, 2,877 JDAMs, 500 GMLRS, 609 SDBs and eight Tomahawks.
Even before the ISIL (Islamic State in Iraq and the Levant) 2014 offensive the U.S. had been striving to replace the large number of guided weapons being used. The rebuilding was hampered by the need to deal with ISIL and other Islamic terrorist threats. There were also budget cuts that, as usual, were taken out of efforts to rebuild the “war reserve” of ammo and other gear needed just in case.
In late 2013 the U.S. Department of Defense suddenly increased the number of JDAM smart bomb kits ordered 17 percent (to 212,588). Over 250,000 JDAM kits have been manufactured since 1998 and the U.S. has been the biggest customer followed by Israel. This is all about stocking up for “The Big One.” The U.S. Air Force (along with the navy, marines, and army) are all moving away from using air power against terrorists and irregular troops, towards what they all refer to as “Bombing Beijing” or North Korea or Iran. This is a major change from how American air power has been used for the past two decades. In that time there has been a lot of bombing but not much opposition to the American aircraft. Since GPS smart bombs and targeting pods were introduced in the 1990s, bomber pilots have had their job reduced to that of a bomb-truck driver.
The U.S. believes the key air weapon will be smart bombs, especially the JDAM and JSOW (powered JDAM). Thus the heavy orders for JDAM, to build up the war reserve in case there is what the planners call a “major war”. Meanwhile, the U.S. has built up a huge arsenal of smart bombs. 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. In 2008, only 5,000 were ordered. But now the orders are over 10,000 a year again. Most of 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 war reserve contains over 100,000 kits, to be used in some unspecified, but big, future conflict. Air warfare planners see the most likely major conflict as one involving China. Despite the dependence on GPS, JDAM has been adapted to resist the jamming and, if that fails there is a backup INS guidance system that, while not as accurate as GPS is accurate enough for most targets.
JDAM smart 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 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. Now the big effort is directed towards using all this new tech to shut down a more determined and capable opponent like China (or Iran or North Korea, two more feisty but less well equipped foes).
A major weapon against Islamic terrorists has been the Hellfire II missile, which weighs 48 kg (106 pounds), carries a 9 kg (20 pound) warhead, and has a range of 8,000 meters. The Hellfire is fast, travelling at about 450 meters a second, meaning that it can hit a target at maximum range in less than 20 seconds. Hellfire is popular for use in urban areas because the small warhead (with only about a kilogram/2.2 pounds of explosives) reduces casualties among nearby civilian (“collateral damage”). The missile is accurate enough to be sent through a window (OK, you have to be really good, and lucky, to do this) because of its laser guidance. Hellfire is the most frequently used missile during the war on terror and especially in battles with ISIL (Islamic State in Iraq and the Levant), which frequently uses civilians as human shields. .
APKWS is a smaller Hellfire type design based on World War II era 70mm unguided rockets. This mini-Hellfire is basically a 13.6 kg (30 pound) 70mm rockets, with a laser seeker, flight controls, a 2.7 kg (six pound) warhead, and a range of about six kilometers. Laser designators on a helicopter, aircraft, or with troops on the ground, are pointed at the target and the laser seeker in the front of the 70mm missile homes in on the reflected laser light.
The army also has 155mm GPS guided 155mm shells (Excalibur). Each 45.5 kg (100 pounds) shell has about 9.1 kg (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 68 kg (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.
Then there's a completely new smart bomb design, the 114 kg (250 pounds) SDB (small diameter bomb). This weapon has a shape that's more missile than bomb (1.78 meters/70 inches long, 190 millimeters in diameter), with the guidance system built in. The smaller blast from the SDB is still pretty substantial (23.2 kg/51 pounds of explosives).
There have been other “smart bomb” designs but you can tell which ones were the most successful by paying attention to what was purchased for the war reserve.