Drone warfare
United States: Estimates for the total people killed in U.S. drone strikes in Pakistan, range from 2,000 to 3,500 militants killed and 158–965 civilians killed. 81 insurgent leaders in Pakistan have been killed. Drone strikes in Yemen are estimated to have killed 846–1,758 militants and 116–225 civilians. 57 Al-Qaeda in the Arabian Peninsula leaders are confirmed to have been killed.
In August 2018, Al Jazeera reported that a Saudi Arabian-led coalition combating Houthi rebels in Yemen had secured secret deals with al-Qaeda in Yemen and recruited hundreds of that group's fighters: "... Key figures in the deal-making said the United States was aware of the arrangements and held off on drone attacks against the armed group, which was created by Osama bin Laden in 1988."
After US president Donald Trump had increased drone strikes by over 400%,his successor Joe Biden reversed course.  Under Biden, drone strikes reportedly decreased.  A Biden administration drone strike in Kabul, Afghanistan in August 2021 killed 10 civilians, including seven children. Later, a drone strike killed Al-Qaeda leader Ayman al-Zawahiri.

Effects: Scholarly opinions are mixed regarding the efficacy of drone strikes. Some studies support that decapitation strikes to kill a terrorist or insurgent group's leadership limit the capabilities of these groups in the future, while other studies refute this. Drone strikes are successful at suppressing militant behavior, though this response is in anticipation of a drone strike rather than as a result of one. Data from the US and Pakistan's joint counter-terrorism efforts show that militants cease communication and attack planning to avoid detection and targeting.
Proponents of drone strikes assert that drone strikes are largely effective in targeting specific combatants. Some scholars argue that drone strikes reduce the amount of civilian casualties and territorial damage when compared to other types of military force like large bombs. Military alternatives to drone strikes such as raids and interrogations can be extremely risky, time-consuming, and potentially ineffective. Relying on drone strikes does not come without risks as U.S. drone usage sets an international precedent on extraterritorial and extrajudicial killings.

Islamic State drone strikes: Small drones and quadcopters have been used for strikes by the Islamic State in Iraq and Syria. A group of twelve or more have been piloted by specially trained pilots to drop munitions onto enemy forces. They have been able to evade ground defense forces.
During the battle for Mosul, the Islamic State was able to kill or wound dozens of Iraqi soldiers by dropping light explosives or 40-millimeter grenades from numerous drones attacking at the same time. Drone strikes were also used to destroy military supplies. Drone footage released by the Islamic State showed bombs being dropped on an ammunitions facility located in Deir ez-Zor, Syria, an area of contested control between the Islamic State and the Syrian government at the time.
In 2017, FBI Director Christopher Wray stated at a Senate hearing that "We do know that terrorist organizations have an interest in using drones ... We have seen that overseas already with some frequency. I think that the expectation is that it is coming here, imminently."
Drone expert Brett Velicovich discussed the dangers of the Islamic State utilizing off the shelf drones to attack civilian targets, claiming in an interview with Fox News that it was only a matter of time before ISIS extremists use of drones to strike civilian targets would become more prevalent and sophisticated.
The overall success rate for drone strikes used by the Islamic State is unclear. The Islamic State may have used drones as a way to gather footage for propaganda purposes, rather than for their military value.

Proliferation in the 2020s: On 6 January 2018, Russian forces thwarted a drone (UAV) swarm attack on the Khmeimim Air Base, the first of this kind in the history of warfare.
In 2020, a Turkish-made UAV loaded with explosives detected and attacked Haftar's forces in Libya with artificial intelligence and without command, according to a report from the UN Security Council's Panel of Experts on Libya published in March 2021. It was considered the first attack carried out by an AI UAV.
The Economist has cited Azerbaijan's highly effective use of drones against Armenia in the 2020 Nagorno-Karabakh war and Turkey's use of drones in the Syrian Civil War as indicating the future of warfare. Noting that it had previously been assumed that drones would not play a major role in conflicts between nations due to their vulnerability to anti-aircraft fire, it suggested that while this might be true for major powers with air defences, it was less true for minor powers. It noted Azerbaijani tactics and Turkey's use of drones as indicating a "new, more affordable type of air power". It also noted that the ability of drones to record their kills enabled a highly effective Azerbaijani propaganda campaign.
On 13 October 2022, a Ukrainian MiG-29 became the first manned plane to go down to a drone during combat. The pilot is claimed to have destroyed a Shahed-136 drone with his cannon. The blast is believed to have brought the plane down and hospitalised the pilot.
Since the 2022 Russian invasion of Ukraine, approximately 30 companies in Ukraine have emerged to mass-produce drones for the war effort. The Ukraine government Ministry of Digital Transformation initiated the "Army of Drones" project, and is attempting to purchase up to 200,000 drones in 2023, aiming to deploy relatively cheap drones against  large advantages Russia has had in military equipment. In 2023, they have also sponsored several competitions where the "dozens of drone developers that have sprung up all over Ukraine" are invited to make simulated attacks on ground targets, or chase fixed-wing drones, or even participate in drone dogfight competitions. One new model that has been successful is the "Baba Yaga" hexacopter, which can carry "44 pounds of payload".

Commercial UCAVs: Commercial UCAVs may be equipped with such weapons as guided bombs, cluster bombs, incendiary devices, air-to-surface missiles, air-to-air missiles, anti-tank guided missiles or other types of precision-guided munitions, autocannons and machine guns. Drone attacks can be conducted by commercial UCAVs dropping bombs, firing a missile, or crashing into a target. Commercial unmanned aerial vehicles (UAVs) can be weaponized by being loaded with dangerous explosives and then crashed into vulnerable targets or detonated above them. They can conduct aerial bombing by dropping hand grenades, mortar shell or other improvised explosive munitions directly above targets. Payloads could include explosives, shrapnel, chemical, radiological or biological hazards. Multiple drones may attack simultaneously in a drone swarm. Drones have been used extensively by both sides for recon and artillery spotting in the Russo-Ukraine War.
Anti-UAV systems are being developed by states to counter the threat of drone strikes. This is, however, proving difficult. According to James Rogers, an academic who studies drone warfare, "There is a big debate out there at the moment about what the best way is to counter these small UAVs, whether they are used by hobbyists causing a bit of a nuisance or in a more sinister manner by a terrorist actor."

Azerbaijan drone warfare: UCAVs were used extensively by the Azerbaijani Army against the Armenian Army during the 2020 Nagorno-Karabakh conflict. These UCAVs included Israeli IAI Harops and Turkish Bayraktar TB2s. As the Bayraktar TB2 utilizes Canadian optics and laser targeting systems, Canada suspended export of its military drone technology to Turkey in October 2020 after allegations that the technology had been used to collect intelligence and direct artillery and missile fire at military positions. After the incident, Aselsan stated that it would begin the serial production and integration of the CATS system to replace the Canadian MX15B.

Russian invasion of Ukraine: During the 2022 Russian invasion of Ukraine, both sides have utilised drones in combat and for reconnaissance, and drones have played an important role in offensives. Ukrainian forces have made extensive use of the Turkish-made Bayraktar TB2 drone throughout the conflict in strikes against Russian forces. Russian forces meanwhile launched waves of Iranian HESA Shahed 136 drones during the October 2022 missile strikes on Ukraine. The main roles of drones in the war, however, are in reconnaissance and artillery spotting. Russian sources claimed to have used a "Stupor anti-drone rifle" to jam the radio controls of Ukrainian drones.
On October 13, 2022, the first recorded instance of an unarmed drone-on-drone combat encounter occurred above the Donetsk region of Ukraine. A Ukrainian DJI Mavic quadcopter was recorded ramming a Russian drone of the same model, resulting in the latter crashing towards the surface below. Another instance of this aerial ramming tactic occurred on November 24, 2022, this time with the Russian DJI Mavic being recorded plummeting towards the ground after a collision with a Ukrainian drone.
On May 9, 2023, a Russian conscript surrendered to (or rather via) a Ukrainian drone.
The average HESA Shahed 136 drone is worth about $20,000. An IRIS-T missile is worth about $430,000 each in comparison. From 13 September until 17 October, open source information suggests that Ukraine has had to spend $28.14 million on defending against these drones.