The digital revolution of the late 20th and early 21st centuries transformed societies and economies, making them reliant on digital infrastructure. This dependency was quickly recognised as a vulnerability in the context of warfare. Cyber warfare emerged as a strategy to exploit these vulnerabilities, aiming to disrupt, degrade, or destroy digital assets of the adversary. This could involve attacks on power grids, financial systems, communication networks, or even military command and control systems. With countries like the US, Russia, China, and others investing heavily in cyber capabilities, it marked the evolution of warfare from purely physical realms to the digital frontier.

While guerrilla warfare, a form of irregular warfare where small groups use hit-and-run tactics, predates many modern technological advancements, the 20th century saw technology shape its emergence and strategies. Communications technology, like radio transmitters, enabled guerrilla fighters to coordinate over vast territories. Modern weaponry, lightweight and portable, made it easier for them to inflict damage and then vanish. Additionally, the availability of anti-tank and anti-aircraft weaponry to non-state actors challenged conventional military superiority. In response, technologically advanced reconnaissance tools and surveillance systems were developed to counter guerrilla tactics. In essence, technology both facilitated guerrilla strategies and propelled the development of counter-insurgency tools.

The concept of total war, where entire societies mobilise for conflict and civilian infrastructure becomes a legitimate target, significantly influenced technological advancements in the 20th century. This concept led to an accelerated development of technologies that could target the enemy's infrastructure, morale, and production capabilities. Strategic bombers, like the B-29 Superfortress, were designed to deliver payloads over long distances and destroy entire cities. The V-2 rockets by Nazi Germany were early predecessors to modern ballistic missiles. Total war also prioritised the development of defence mechanisms against such threats, leading to innovations like radar systems and anti-aircraft weaponry. Essentially, the complete immersion of societies in the war effort drove a rapid technological arms race.

Radar and sonar had profound impacts on naval warfare in the 20th century. Before radar, naval battles were largely constrained to visual ranges. With radar's introduction, ships could detect adversaries at significantly greater distances, even in poor visibility conditions, thereby changing naval tactics and strategies. Sonar, specifically, revolutionised anti-submarine warfare. Submarines, once stealthy hunters of the deep, became vulnerable as surface ships could detect them using sonar. This forced submarines to operate at greater depths and adopt evasive tactics. Additionally, the game of cat-and-mouse between submarines and anti-submarine warfare units intensified, leading to further technological innovations in both domains.

Missile technology, especially intercontinental ballistic missiles (ICBMs), significantly influenced the dynamics of Cold War confrontations between the US and the Soviet Union. ICBMs could deliver nuclear warheads over vast distances, effectively placing each superpower within striking range of the other. This posed a severe threat of mutual destruction, leading to the doctrine of Mutual Assured Destruction (MAD). MAD meant that any direct nuclear confrontation would result in the total annihilation of both parties, thus discouraging any first use of nuclear weapons. Furthermore, missile technology spurred the space race, as rockets were dual-purpose: they could launch both warheads and satellites or spacecraft. The Cuban Missile Crisis of 1962, revolving around the placement of Soviet missiles in Cuba, underscores the central role missile technology played in Cold War geopolitics.