Suppression of enemy air defenses (SEAD /ˈsiː-æd/), also known in the United States as "Wild Weasel" and (initially) "Iron Hand" operations, are military actions to suppress enemy surface-based air defenses, including surface-to-air missiles (SAMs), anti-aircraft artillery (AAA), and related systems such as early-warning radar and command, control and communication functions.

Suppression can be accomplished by physically destroying the systems or by disrupting and deceiving them through electronic warfare. In modern warfare, SEAD missions can constitute up to 30% of sorties launched in the first week of combat and continue at a reduced rate through the rest of a campaign. One-quarter of American combat sorties in recent conflicts have been SEAD missions. They are generally associated with aircraft, but may be performed using any means, including ground forces.

In some contexts, destruction of enemy air defenses (DEAD) refers to physical destruction of air defense targets, while SEAD applies to sorties which discourage enemy use of air-defense radar assets out of fear of placing the assets in jeopardy.

Primitive operations akin to SEAD emerged during the Second World War: efforts to degrade enemy ground radar stations. The Vietnam War saw the first SEAD missions performed by dedicated aircraft. Other early conflicts with SEAD efforts included the 1982 Falklands War, over Port Stanley, and the 1982 Lebanon War, in the Beqaa Valley. The 1990s saw extensive use of SEAD, particularly during the Gulf War. In the 1999 NATO bombing of Yugoslavia, air defenses proved less vulnerable and more effective; the downing of an F-117A Nighthawk marked the first combat loss of a stealth aircraft. In the Iraq War of the 2000s, coalition aircraft targeted Iraqi SAMs during the opening phase of the conflict, yet aerial strikes were usually performed from stand-off distances to avoid these defenses, and low-level flight was avoided. In the 2022 Russian invasion of Ukraine, while many Ukrainian air defence facilities were reportedly destroyed or damaged in the first days of the war by Russian air strikes, Russia may not have been able to gain aerial superiority; it has been alleged that Ukrainian mid-range SAM sites have forced planes to fly low, but this makes them vulnerable to shoulder-launched surface-to-air missiles.

Before the Vietnam War, SEAD was an undefined mission: although attempts to destroy enemy air defense sites were undertaken, they were done so by individual aircraft against specific targets or operations, not as part of an overall strategy or doctrine of defense suppression. Near the end of the Second World War, US Navy pilots developed a doctrine that could be considered the first example of SEAD. When attacking enemy warships, US Navy fighters would attack enemy warships with machine guns and rockets to distract and or kill the enemy anti aircraft gunners while the torpedo and dive bombers could move in and more accurately target the ship. While crude, these tactics were frequently effective for their time.

During the Battle of Britain, the German Luftwaffe attempted to destroy Great Britain's Chain Home radar stations in order to degrade the British air defense network. However, German High Command failed to realize the efficiency of not only the radar stations themselves but the command and control system directing Britain's air defenses. After initial optimism regarding the radar sites' destruction, it was eventually decided to halt these attacks altogether except for exceptional circumstances. As the air war in Europe shifted in favor of the Allies, the Germans relied heavily on their AAA to defend against bombing attacks. This was borne out in Allied aircraft losses between 1943 and 1944, where losses to enemy fighters were cut in half but losses to flak increased tenfold.

Understanding the importance of Germany's radar sites, the Allies directed attacks against these installations and introduced new technology to counteract the effects of radar-directed AAA, including CARPET (US) and WINDOW (UK). A change in tactics saw bomber formations flying higher and more spread out to avoid the effects of flak. Bombing missions were also carried out to accomplish the physical destruction of AAA sites, using imagery intelligence to locate the weapons and employing both heavy bombers and fighter-bombers to destroy them. The P-47 Thunderbolt in particular was chosen for this task due to its ability to survive enemy fire. The effect of these missions varied, with losses suffered by fighter-bombers much higher—up to 40% in some cases—on account of their low-altitude attacks. Artillery also played a major role in suppressing air defenses, with the British Army the first to develop what became known as counterflak or "Apple Pie" missions. These missions were first employed to limited effect during the Battle of France but matured as the war progressed. The largest SEAD mission in history took place on March 24, 1945, when artillery forces of the British XII Corps attempted to knock out the local German air defense network in support of Operation Varsity. Although twenty-four thousand artillery shells were fired over the course of twenty-two minutes at some one hundred targets, the mission was unsuccessful due to inaccurate targeting data and insufficient firepower.

In the Pacific Theater, the Japanese had made only limited progress in developing radar for air defense and what systems they did have were primitive and easy to avoid. Nevertheless, as the Americans began the bombing campaign against Japan there was concern over the large number of radar sites located on the home islands. For this purpose B-24 Liberators and B-29 Superfortresses were fitted with radar-homing devices to conduct "ferret" missions to locate and identify radar transmissions. The information brought back from these missions was used to outfit other B-29s with radar jammers and chaff to confuse Japanese air defense radars as they conducted their missions. B-25 Mitchells were also outfitted with radar-homing equipment and used to lead "hunter-killer" teams of other B-25s in locating and destroying Japanese early-warning radar sites.