Editing Joint Direct Attack Munition (section)

===Operational use===
[[File:Falcon JDAM LGBs (1).jpg|thumb|JDAMs loaded under the left wing of an [[F-16 Fighting Falcon]], with a [[LITENING targeting pod|LITENING II]] Targeting Pod visible beneath the fuselage]]

Guidance is facilitated through a tail control system and a [[Global Positioning System|GPS]]-aided [[inertial navigation system]] (INS). The navigation system is initialized by transfer alignment from the aircraft that provides position and velocity vectors from the aircraft systems. Once released from the aircraft, the JDAM autonomously navigates to the designated target coordinates. Target coordinates can be loaded into the aircraft before takeoff, manually altered by the aircrew in flight prior to weapon release, or entered by a datalink from onboard targeting equipment, such as the [[LITENING targeting pod|LITENING II]] or [[Lockheed Martin Sniper XR|"Sniper"]] targeting pods. In its most accurate mode, the JDAM system will provide a minimum weapon accuracy CEP of {{convert|5|m|ft|order=flip}} or less when a GPS signal is available. If the GPS signal is jammed or lost, the JDAM can still achieve a {{convert|30|m|ft|order=flip|adj=on}} CEP or less for free flight times up to 100 seconds.<ref name=USAFfactsheet />

The introduction of GPS guidance to weapons brought several improvements to air-to-ground warfare. The first is a real all-weather capability since GPS is not affected by rain, clouds, fog, smoke, or artificial obscurants. Previous precision guided weapons relied on seekers using infrared, visual light, or a reflected laser spot to "see" the ground target. These seekers were not effective when the target was obscured by fog and low altitude clouds and rain (as encountered in Kosovo), or by dust and smoke (as encountered in Desert Storm).{{Citation needed|date=January 2013}}

The second advantage is an expanded launch acceptance region (LAR). The LAR defines the region that the aircraft must be within to launch the weapon and hit the target. Non-GPS based precision guided weapons using seekers to guide to the target have significant restrictions on the launch envelope due to the seeker field of view. Some of these systems (such as the [[Paveway]] I, II, and III) must be launched so that the target remains in the seeker field of view throughout the weapon trajectory (or for lock-on-after-launch engagements, the weapon must be launched so that the target is in the field of view during the terminal flight). This requires the aircraft to fly generally straight at the target when launching the weapon.

This restriction is eased in some other systems, such as the [[GBU-15]] and the [[AGM-130]], through the ability of a Weapon System Operator (WSO) in the aircraft to manually steer the weapon to the target. Using a WSO requires a data link between the weapon and the controlling aircraft and requires the controlling aircraft to remain in the area (and possibly vulnerable to defensive fire) as long as the weapon is under manual control. Since GPS-based flight control systems know the weapon's current location and the target location, these weapons can autonomously adjust the trajectory to hit the target. This allows the launch aircraft to release the weapon at very large off-axis angles including releasing weapons to attack targets behind the aircraft.{{Citation needed|date=January 2013}}

[[File:US Navy 030321-N-3235P-510 On the flight deck aboard the aircraft carrier USS Harry S. Truman (CVN-75), 2000 lbs GBU-31 Joint Direct Attack Munitions (JDAM) are transported to the flight deck.jpg|thumb|JDAMs prior to being loaded for operations over Iraq, 2003]]

The third advantage is a true "[[fire-and-forget]]" capability in which the weapon does not require any support after being launched. This allows the launching aircraft to leave the target area and proceed to its next mission immediately after launching the GPS guided weapon.{{Citation needed|date=January 2013}}

Another important capability provided by GPS-based guidance is the ability to completely tailor a flight trajectory to meet criteria other than simply hitting a target. Weapon trajectories can be controlled so that a target can be impacted at precise headings and vertical angles. This provides the ability to impact perpendicular to a target surface and minimize the angle of attack (maximizing penetration), detonate the warhead at the optimum angle to maximize the warhead effectiveness, or have the weapon fly into the target area from a different heading than the launch aircraft (decreasing the risk of detection of the aircraft). GPS also provides an accurate time source common to all systems; this allows multiple weapons to [[Loiter (aeronautics)|loiter]] and impact targets at preplanned times and intervals.{{Citation needed|date=February 2012}}

In recognition of these advantages, most weapons including the Paveway, GBU-15, and the AGM-130 have been upgraded with a GPS capability. This enhancement combines the flexibility of GPS with the superior accuracy of seeker guidance.{{Citation needed|date=January 2013}}

[[File:GBU-38 munition explosions in Iraq.jpg|thumb|GBU-38 explosions in Iraq in 2008.]]

Despite their precision, JDAM employment has risks. On 5 December 2001, a JDAM dropped by a [[B-52]] in [[Afghanistan]] nearly killed [[Hamid Karzai]] while he was leading anti-[[Taliban]] forces near Sayd Alim Kalay alongside a [[US Army Special Forces]] (SF) team. A large force of Taliban [[soldier]]s had engaged the combined force of Karzai's men and their American SF counterparts, nearly overwhelming them. The SF commander requested [[Close Air Support]] (CAS) to strike the Taliban positions in an effort to stop their advance. A JDAM was subsequently dropped, but instead of striking the Taliban positions, it struck the Afghan/American position, killing three and injuring 20. An investigation of the incident determined that the U.S. Air Force Tactical Control Party (TACP) attached to the Special Forces team had changed the battery in the [[Precision Lightweight GPS Receiver|GPS receiver]] at some point during the battle, thereby causing the device to return to "default" and "display its own coordinates." Not realizing that this had occurred, the TACP relayed his own coordinates to the delivery aircraft.<ref name="friendly">{{cite web |author=Burgess |first=Mark |date=12 June 2002 |title=Killing Your Own: The Problem of Friendly Fire During the Afghan Campaign |url=http://www.cdi.org/terrorism/killing.cfm |url-status=dead |archive-url=https://web.archive.org/web/20100317163641/http://www.cdi.org/terrorism/killing.cfm |archive-date=17 March 2010 |access-date=5 October 2010 |publisher=CDI}}</ref><ref>{{Cite web |last=Ladkin |first=Peter B. |title=Checking and Comparison of WB-Graphs |url=http://www.rvs.uni-bielefeld.de/publications/Papers/ladkin_WBG_Comparison.pdf |url-status=live |archive-url=https://web.archive.org/web/20230404121331/http://www.rvs.uni-bielefeld.de/publications/Papers/ladkin_WBG_Comparison.pdf |archive-date=4 April 2023 |website=University of Bielefeld |page=9}}</ref>

On 5 May 2023, during the [[2022 Russian invasion of Ukraine]], MSN reported that Russia was able to [[Radio jamming|jam]] the [[GPS]] guidance system to cause JDAMs to miss their targets. The leaked Pentagon document described the JDAMs as being particularly susceptible to the disruption.<ref>{{Cite web |last1=Marquardt |first1=Alex |last2=Bertrand |first2=Natasha |last3=Cohen |first3=Zachary |date=6 May 2023 |title=Russia's jamming of US-provided rocket systems complicates Ukraine's war effort |url=https://edition.cnn.com/2023/05/05/politics/russia-jamming-himars-rockets-ukraine/index.html |url-status=live |archive-url=https://web.archive.org/web/20231214005622/https://edition.cnn.com/2023/05/05/politics/russia-jamming-himars-rockets-ukraine/index.html |archive-date=14 December 2023 |access-date= |website=CNN |language=en-US}}</ref>

On 6 June 2023, the [[Royal United Services Institute]] (RUSI) released a commentary by an [[electronic warfare]] (EW) expert on the jamming of JDAMs by Russian forces. The paper notes that the Russian [[R-330Zh Zhitel]] has had impacted GPS signals that JDAMs rely on. GPS signals are "very weak by the time they have travelled the 10,900 nautical miles (20,200 km) from the satellite to Earth", making them "easy to jam with comparatively little power". In the "early 2000s" the US military rolled out the [[Selective availability anti-spoofing module]] (SAASM), along with encrypted military M-code GPS signaling to ensure that the JDAM only accepts signals with correct encryption and rejects all other signals. However, according to one electronic warfare (EW) expert who spoke to RUSI, despite the mentioned steps to increase jamming resiliency, the "sheer brute force" of a powerful jamming signal can prevent the JDAM's [[global navigation satellite system]] (GNSS) receiver from obtaining the encrypted signal.

Counter-EW systems, while classified, might allow a JDAM to recognize a jamming signal and its direction and "block out" signals coming from that direction. A GNSS receiver will "typically need to 'see' – that is have an uninterrupted Line-of-Sight (LOS) with – at least four satellites", and will "often" have more satellites available to it. Thus, blocking signals from one direction might not affect the receiver's ability to "see" other satellites. Russian forces may choose to respond by placing more jammers in order to deny a line of sight to the satellites that it requires. Russian EW units might also have the ability to spoof or fake the M-Code that it confuses the JDAM as to its location and time. Ukrainian forces have been able to locate Russian jammers and hit them with "kinetic" attacks such as artillery. Several Russian EW units have been targeted and lost equipment.<ref>{{Cite web |author=Malyasov |first=Dylan |date=21 April 2023 |title=Ukrainian forces blow up modern Russian electronic warfare system |url=https://defence-blog.com/ukrainian-forces-blow-up-modern-russian-electronic-warfare-system/ |url-status=live |archive-url=https://web.archive.org/web/20230928035134/https://defence-blog.com/ukrainian-forces-blow-up-modern-russian-electronic-warfare-system/ |archive-date=28 September 2023 |access-date=26 September 2022 |website=Defence Express |language=en-US}}</ref><ref>{{Cite web |author=Withington |first=Thomas |date=6 June 2023 |title=Jamming JDAM: The Threat to US Munitions from Russian Electronic Warfare |url=https://www.rusi.org/explore-our-research/publications/commentary/jamming-jdam-threat-us-munitions-russian-electronic-warfare |url-status=live |archive-url=https://web.archive.org/web/20231208175445/https://www.rusi.org/explore-our-research/publications/commentary/jamming-jdam-threat-us-munitions-russian-electronic-warfare |archive-date=8 December 2023 |access-date=10 June 2023 |website=Royal United Services Institute |language=en-US}}</ref><ref>{{Cite web |author=Mizokami |first=Kyle |date=21 April 2023 |title=GPS-Guided Bombs Should've Been Ukraine's Ace in the Hole. Then, Russian Jamming Stepped In |url=https://www.popularmechanics.com/military/weapons/a43591694/russian-jamming-gps-guided-bombs/ |url-status=live |archive-url=https://web.archive.org/web/20230501213936/https://www.popularmechanics.com/military/weapons/a43591694/russian-jamming-gps-guided-bombs/ |archive-date=1 May 2023 |access-date=10 June 2023 |website=Popular Mechanics |language=en-US}}</ref>

On 13 August 2024, Ukrainian Su-27 launched a [[JDAM]] at a Russian command post in [[Tetkino]], which was reportedly destroyed.<ref>{{cite news |title=Ukrainian Jets Join The Invasion Of Russia's Kursk Oblast—And Blow Up A Russian Command Post |url=https://www.forbes.com/sites/davidaxe/2024/08/13/ukrainian-jets-join-the-invasion-of-russias-kursk-oblast-and-blow-up-a-russian-command-post/|author=David Axe|access-date=14 August 2024 |work=Forbes |date=14 August 2024 }}</ref>

In December 2023, the WSJ report stated that [[United States support for Israel in the Gaza war|US arms shipments to Israel]] since the start of the [[Gaza war]] included approximately 3,000 JDAMs.<ref>{{cite news |title=US sends 'bunker buster' bombs to Israel for war on Gaza, report says |url=https://www.aljazeera.com/news/2023/12/2/us-gives-bunker-buster-bombs-to-israel-for-war-on-gaza-report |agency=Al-Jazeera |date=2 December 2023}}</ref> Israeli [[F-15I]] fighter jets are believed to have used [[BLU-109 bomb|BLU-109]] [[bunker buster|bunker buster bombs]] with JDAM guidance kits in the [[2024 Hezbollah headquarters strike|strikes]] that killed [[Hezbollah]] leader [[Hassan Nasrallah]] in Beirut, Lebanon on 27 September 2024.<ref>{{cite news |title=Israel likely used U.S.-made 2,000-pound bombs in Nasrallah strike, visuals show |url=https://www.washingtonpost.com/world/2024/09/29/israel-bomb-beirut-nasrallah-death/ |newspaper=The Washington Post |date=29 September 2024}}</ref><ref>{{cite news |title= US-made 2,000-pound bombs likely used in strike that killed Hezbollah chief Nasrallah, CNN analysis shows|url=https://edition.cnn.com/2024/09/30/middleeast/israel-attack-nasrallah-2000-pound-bombs-intl/index.html |work=CNN |date=30 September 2024}}</ref>