One of the most popular and effective air-to-ground weapons used in the current bombing campaign in Iraq and Syria is the British Brimstone (a Hellfire variant that can be used by jet fighters). Brimstone entered service in 2005 and was widely used in Libya in 2011 and there was particularly effective. Despite that Brimstone can only be used by one aircraft, the 1970s era Tornado GR4. This aircraft is only used by the Britain and Saudi Arabia and is being replaced by the Typhoon. Meanwhile a new Brimstone 2 entered service in 2015. Britain has been working on getting Typhoon equipped to handle both versions of Brimstone and in late 2017 most of the development and testing for this was successfully completed. In mid-2018 Brimstone should be in service on the Typhoon. Originally this was to happen in 2021 but then it was realized that Typhoon was being rapidly retired and 2018 was a more realistic date.
One reason for the Brimstone success in Libya was the use of three rail “Cobham launcher.” The Cobham launcher enabled Tornado to carry twelve Brimstones and Typhoon could carry up to 18 Brimstones. In 2015 the Brimstone 2 entered service, again only on the Tornado but able to use the three rail launcher. Brimstone 2 has longer range (fired from jets) increased from 20 kilometers to 60 kilometers along with improvements in accuracy and reliability (it uses explosives that are less likely to detonate accidentally). At the new max range the Brimstone takes up to three minutes to reach its target.
Work is also underway to get Brimstone 2 working on the British Reaper UAVs and AH-64 gunships. Both of these aircraft already use Hellfire but Brimstone 2 is a major improvement over Hellfire for UAVs and helicopter gunships.
Originally developed as an upgraded version of the American Hellfire, Brimstone ended up as a Hellfire in general shape only. Weighing the same as the Hellfire (48.5 kg/107 pounds), Brimstone was designed to be fired by fighter-bombers, not just (as with Hellfire) from helicopters and UAVs. Aircraft can carry a lot of these lightweight missiles. These are perfect for small targets, including vehicles, which need to be hit, without causing injuries to nearby civilians or friendly troops. Brimstone entered service in 2005 and only a few thousand were produced. Use was low in Afghanistan, but was much higher in Libya. And that caused other nations to pay attention and seek to get Brimstone for their own use. This was a problem because production was unable to rapidly increase and production lines were already in the midst of retooling for the new Brimstone 2, which included a dual-mode (radar and laser) seeker to its Brimstone missiles. The Brimstone radar seeker makes it easier to use the missile in "fire and forget" mode. The laser seeker is more accurate (to within a meter or two of the aim point.) The nine kilogram (20 pound) Brimstone warhead is sufficient to destroy vehicles, without causing a lot of casualties to nearby civilians. British fighter pilots have become quite good at coming in low and taking out individual vehicles with Brimstone missiles. Carrying a dozen or more Brimstones, a fighter-bomber can easily use all of them in one sortie, all the while staying out of range of ground fire.
The U.S. has not adopted the Brimstone nor modified the Hellfire for “fast movers”. Instead the Americans have adopted an even smaller laser guided missile, the APKWS (Advanced Precision Kill Weapons System). This 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. Since 2013 the U.S. has allowed APKWS on any jets equipped to fire it. At this point that includes the F-18C, the AV-8B, the F-35 and the A-10. As more of these jet pilots use APKWS (or Brimstone) more want it. Modern targeting pods make it easier to spot ground targets from a high altitude and promptly launch a laser guided missile.