Missile defense
The actual warhead may simply pass by undetected, or rejected as a threat.

Cooled shrouds: Another common countermeasure used to fool missile defense systems are the implementation of cooled shrouds surrounding attacking missiles. This method covers the entire missile in a steel containment filled with liquid oxygen, nitrogen, or other sub-zero coolants that prevent the missile from being easily detected. Because many missile defense systems use infrared sensors to detect the heat traces of incoming missiles, this capsule of extremely cold liquid either renders the incoming missile entirely invisible to detection or reduces the system's ability to detect the incoming missile fast enough.

Other types of infrared stealth: Another commonly applied countermeasure to missile defense is the application of various low-emissivity coatings. Similar to cooled shrouds, these warheads are fully coated with infrared reflective or resistant coatings that allow similar resistance to infrared detection that cooled shrouds do. Because the most effective coating discovered so far is gold, though, this method is often overstepped by cooled shrouds.

Biological and chemical weapons: This is perhaps the most extreme approach to countering missile defense systems that are designed to destroy ICBMs and other forms of nuclear weaponry. Rather than using many missiles equipped with nuclear warheads as their main weapon of attack, this idea involves the release of biological or chemical sub-munition weapons or agents from the missile shortly after the boost phase of the attacking ICBM. Because missile defense systems are designed with intent to destroy main attacking missiles or ICBMs, this system of sub-munition attack is too numerous for the system to defend against while also distributing the chemical or biological agent across a large area of attack.
There is currently no proposed countermeasure to this type of attack except through diplomacy and the effective banning of biological weaponry and chemical agents within war. However, this does not guarantee that this countermeasure to missile defense system will not be abused via extremists or terrorists. An example of this severe threat can be further seen in North Korea's testing of anthrax tipped ICBMs in 2017.

Dynamic trajectories: Countries including Iran and North Korea may have sought missiles that can maneuver and vary their trajectories in order to evade missile defense systems.
In March 2022, when Russia used a hypersonic missile against Ukraine, Joe Biden characterized the weapon as "almost impossible to stop". Boost-glide hypersonic weapons shift trajectory to evade current missile-defense systems.
Glide Phase Interceptor (GPI) will provide defense against maneuvering hypersonic weapons.

Multiple independently targetable re-entry vehicles: Another way to counter an ABM system is to attach multiple warheads that break apart upon reentry. If the ABM is able to counter one or two of the warheads via detonation or collision the others would slip through radar either because of limitations on ABM firing speeds or because of radar blackout caused by plasma interference. The first MRV was the Polaris A-3 which had three warheads and was launched from a submarine. Before regulations on how many warheads could be stored in a MIRV, the Soviets had up to twenty to thirty attached to ICBMs.

Jammers: Jammers use radar noise to saturate the incoming signals to the point where the radar cannot discern meaningful data about a target's location with meaningless noise. They can also imitate the signal of a missile to create a fake target.  They are usually spread over planned missile paths to enemy territory to give the missile a clear path to their target. Because these jammers take relatively little electricity and hardware to operate, they are usually small, self-contained, and easily dispersible.

Command and Control: 

Command and control, battle management, and communications (C2BMC): Command and control, battle management, and communications (C2BMC) systems are hardware and software interfaces that integrate a multitude of sensory information at a centralized center for the ballistic missile defense system (BMDS). The command center allows for human management in accordance to the incorporated sensory information- BMDS status, system coverage, and ballistic missile attacks. The interface system helps build an image of the battle scenario or situation which enables the user to select the optimal firing solutions.

The first C2BMC system became operational in 2004. Since then, many elements have been added to update the C2BMC, which act to provide further sensory information and allow for enhanced communications between combatant commanders. A C2BMC is even capable of initiating live planning system before any engagement has even started.

GMD fire control and communication: The function of ground-based midcourse defense (GMD) systems is to provide combatants the ability to seek and destroy intermediate- and long-range ballistic missiles en route to the US homeland.  Data are transmitted from the defense satellite communication system, and compiles an image using the coordinated information. The system is able to relay real-time data once missiles have been launched. The GMD can also work to receive information from the C2BMC, which allows Aegis SPY-1, and TPY-2 to contribute to the defense system.
A problem with GMD is that the ground systems have increasingly becoming obsolete as the technology was initially installed as early as the 1990s. So, the ground sensors had been replaced sometime in 2018. The update was to add the capability of handling up to 44 systems; it would also reduce overlapping redundancies and inefficiencies.
Missiles are a link that connects communication between land, air, and sea forces to support joint operations and improve operability. The system is intended to improve the interoperability for joint operations of NATO and coalition forces. Link-16 is also used by the US Army and Navy for air and sea operations. An important feature of Link-16 is its ability to broadcast information simultaneously to as many users as needed. Another feature of Link-16 is its ability to act as nodes, which allows for a multitude of distributed forces to operate cohesively.
The newest generation of Link-16 is the multifunctional information distribution system low-volume terminal (MIDS LVT). It is a much smaller unit that can be fitted on air, ground, and sea units to incorporate data. The MIDS LVT terminals are installed on most bombers, aircraft, UAVs, and tankers, allowing for the incorporation of most air defense systems.

Integrated Air and Missile Defense Battle Command System: The Integrated Air and Missile Defense Battle Command System (IBCS) is an unified command and control network developed by the US Army. It is designed to integrate data relay between weapon launchers, radars, and the operators, which allows air-defense units to fire interceptors with information being relayed among radars. The advantage of such a system is it can increase the area an air unit can defend and reduce interceptor spending by ensuring than no other air defense unit would engage the same target. The IBCS will be able to integrate with air defense networks of foreign military as the global C2BMC system.

IBCS engagement stations will integrate raw  data from multiple sensors and process it into a single air picture, and choose elect different weapons and launcher locations depending on the detected threat instead of being limited to particular unit capabilities.
The IBCS system is intended to be operational in 2019; between 2016 and 2017, implementation of IBCS had to be put on hold due to software issues with the system. In 2021, F-35 sensor data were linked via airborne gateway to ground-based IBCS, to conduct a simulated Army fires exercise, for future Joint All-Domain Command and Control (JADC2).

History: The problem was first studied during the last year of the Second World War. The only countermeasure against the V-2 missile that could be devised was a massive barrage of anti-aircraft guns. Even if the missile's trajectory were accurately calculated, the guns would still have a small probability of destroying it before impact with the ground. Also, the shells fired by the guns would have caused more damage than the actual missile when they fell back to the ground. Plans for an operational test began anyway, but the idea was rendered moot when the V-2 launching sites in the Netherlands were captured.
In the 1950s and 1960s, missile defense meant defense against strategic (usually nuclear-armed) missiles. The technology mostly centered around detecting offensive launch events and tracking inbound ballistic missiles, but with limited ability to actually defend against the missile. The Soviet Union achieved the first nonnuclear intercept of a ballistic missile warhead by a missile at the Sary Shagan antiballistic missile defense test range on 4 March 1961. Nicknamed the "Griffon" missile system, it would be installed around Leningrad as a test

Throughout the 1950s and 1960s, the United States Project Nike air defense program focused initially on targeting hostile bombers before shifting focus to targeting ballistic missiles. In the 1950s, the first United States anti-ballistic missile system was the Nike Hercules, which had the ability to intercept incoming short-range ballistic missiles, but not intermediate-range ballistic missiles (IRBMs) or ICBMs. This was followed by the Nike Zeus, which was capable of intercepting ICBMs by using a nuclear warhead, upgraded radar systems, faster computers, and control systems that were more effective in the upper atmosphere. However it was feared the missile's electronics may be vulnerable to x-rays from a nuclear detonation in space. A program was started to devise methods of hardening weapons from radiation damage. By the early 1960s the Nike Zeus was the first anti-ballistic missile to achieve hit-to-kill (physically colliding with the incoming warhead).