Space warfare
History: 

1950s: During the early Cold War, a survivable reconnaissance asset was considered highly valuable. In a time before satellites, this meant building an aircraft that could fly higher or faster, or both, compared to any interceptor that would try to bring it down. Notably, the United States would introduce the U-2 spy plane in 1956. It was thought, at the time of its introduction, that the plane’s service ceiling of 24,000 metres (80,000 ft) would render it immune to Soviet aircraft, missiles, and radar. That was the case until the 1960 U-2 incident, where a United States U-2 spy plane was shot down by the Soviet Air Defense Forces’ S-75 Dvina (SA-2 Guideline) surface-to-air missile while conducting photographic aerial reconnaissance deep inside Soviet territory.
Three years before the incident, in 1957, a modified R-7 rocket carried the world's first artificial satellite, Sputnik 1, into an orbit hundreds of kilometers above sea level, notably beyond the reach of any existing weapons system. While Sputnik 1 held no military value, only transmitting radio signals back to Earth for three weeks, its launch sparked the beginning of the Space Race. This spurred the United States to hasten and re-emphasize its space programs, culminating in the Explorer program, which launched the first American satellite into orbit in 1958. In tandem with the effort to achieve superior spaceflight capability over the other, the United States and the Soviet Union began to develop space warfare capabilities.

1960s: Early efforts to conduct space warfare were directed at space-to-space warfare, as ground-to-space systems were considered to be too slow and too isolated by Earth's atmosphere and gravity to be effective at the time. The history of active space warfare development goes back to the 1960s when the Soviet Union began the Almaz project, a project designed to give them the ability to do on-orbit inspections of satellites and destroy them if needed.  Similar planning in the United States took the form of the Blue Gemini project, which consisted of modified Gemini capsules that would be able to deploy weapons and perform surveillance.
One early test of electronic space warfare, the so-called Starfish Prime test, took place in 1962 when the United States exploded a ground-launched nuclear weapon in space to test the effects of an electromagnetic pulse. The result was a deactivation of many then-orbiting satellites, both American and Soviet. The deleterious and unfocused effects of the EMP test led to the banning of nuclear weapons in space in the Outer Space Treaty of 1967. (See high-altitude nuclear explosion.)
In the early 1960s, the U.S. military produced a film called Space and National Security which depicted space warfare.

1970s–1990s: Through the 1970s, the Soviet Union continued their project and test-fired a cannon to test space station defense. This was considered too dangerous to do with a crew on board, however, so the test was conducted after the crew had returned to Earth.
A 1976 Soviet report suggested that the design of the Space Shuttle had been guided by a requirement to deliver a payload- such as a bomb- over Russia and return to land after a single orbit. This may have been a confusion based on requirements 3A and 3B for the shuttle's design, which required the craft to be able to deploy or retrieve an object from a polar orbit in a single pass.
Both the Soviets and the United States developed anti-satellite weaponry designed to shoot down satellites. While early efforts paralleled other space-to-space warfare concepts, the United States was able in the 1980s to develop ground-to-space laser anti-satellite weapons. None of these systems are known to be active today; however, a less powerful civilian version of the ground-to-space laser system is commonly used in the astronomical technique of adaptive optics.
In 1984, the Strategic Defence Initiative (SDI) was proposed. It was nicknamed Star Wars after the popular science fiction franchise Star Wars.
In 1985, the United States demonstrated its conventional ASAT capabilities by launching an ASM-135 ASAT from an F-15 to shoot down the Solwind P78-1, an American research satellite, from its 555-kilometre (345 mi) orbit.

Since 2000: The People's Republic of China successfully tested (see 2007 Chinese anti-satellite missile test) a ballistic missile-launched anti-satellite weapon on January 11, 2007. This resulted in harsh criticism from the United States of America, Britain, and Japan.
The U.S. developed an interceptor missile, the SM-3, testing it by hitting ballistic test targets while they were in space. On February 21, 2008, the U.S. used an SM-3 missile to destroy a spy satellite, USA-193, while it was 247 kilometers (133 nautical miles) above the Pacific Ocean.
Japan fields the U.S.-made SM-3 missile, and there have been plans to base the land-based version in Romania and Vietnam.
In March 2019, India shot down a satellite orbiting in a low Earth orbit using an ASAT missile during an operation code named Mission Shakti, thus making its way to the list of space warfare nations, establishing the Defense Space Agency the following month, followed by its first-ever simulated space warfare exercise on July 25 which would inform a joint military space doctrine.
In July 2019, Emmanuel Macron "called for a space high command to protect" France's satellites. This was followed by a plan released by military officials. French Defense Minister, Florence Parly, announced a space weapons program that would move the country's space surveillance strategy towards active protection of its assets in space, e.g., satellites. The projects outlined include: patrolling nano-satellites swarms, ground-based laser systems to blind spying satellites, and machine guns mounted on satellites.
Starlink, SpaceX's large low Earth orbit satellite constellation, was extensively used for warfare following Russia's invasion of Ukraine after the country's previous satcom provider Viasat were cyberattacked in the first few days of the invasion. Starlink was used for defense and attacks on Russian positions, with Starlink terminals being namely strapped on strike drones and sea drones. SpaceX vowed and acted against the use of their Starlink service for active warfare, while Russia launched cyberattacks against Starlink and threatened of striking Starlink satellites directly in retaliation.
On October 31, 2023, as part of the Israel–Hamas War, Israel intercepted a Houthi ballistic missile with its Arrow 2 missile defense system. According to Israeli officials, the interception occurred above Earth's atmosphere above the Negev Desert, making it the first instance of space combat in history.

Theoretical space weaponry: 

Ballistic warfare: In the late 1970s and through the 1980s, the Soviet Union and the United States theorized, designed and in some cases tested a variety of weaponry designed for warfare in outer space. Space warfare was seen primarily as an extension of nuclear warfare, and many theoretical systems were based around the destruction or defense of ground and sea-based missiles. Space-based missiles were not attempted due to the Outer Space Treaty, which banned the use, testing or storage of nuclear weapons outside the Earth's atmosphere. When the U.S. gained "interest in utilizing space-based lasers for ballistic missile defense", two facts emerged. One being that the ballistic missiles are fragile and two, chemical lasers project missile killing energy (3,000 kilometers). This meant that lasers could be put into space to intercept a ballistic missile.
Systems proposed ranged from measures as simple as ground and space-based anti-missiles to railguns, space based lasers, orbital mines and similar weaponry. Deployment of these systems was seriously considered in the mid-1980s under the banner of the Strategic Defense Initiative announced by Ronald Reagan in 1983, using the term "evil empire" to describe the Soviets (hence the popular nickname "Star Wars"). If the Cold War had continued, many of these systems could potentially have seen deployment: the United States developed working railguns, and a laser that could destroy missiles at range, though the power requirements, range, and firing cycles of both were impractical. Weapons like the space-based laser was rejected, not just by the government, but by universities, moral thinkers, and religious people because it would have increased the waging of the arms race and questioned the United States' role in the Cold War.

Electronic warfare: With the end of the Cold War and continued development of satellite and electronics technology, attention was focused on space as a supporting theatre for conventional warfare. Currently, military operations in space primarily concern either the vast tactical advantages of satellite-based surveillance, communications, and positioning systems or mechanisms used to deprive an opponent of said tactical advantages.

Accordingly, most space-borne proposals which would traditionally be considered "weapons" (a communications or reconnaissance satellite may be useful in warfare but isn't generally classified as a weapon) are designed to jam, sabotage, and outright destroy enemy satellites, and conversely to protect friendly satellites against such attacks. To this end, the US (and presumably other countries) is researching groups of small, highly mobile satellites called "microsats" (about the size of a refrigerator) and "picosats" (approximately 1 cubic foot (≈27 litres) in volume) nimble enough to maneuver around and interact with other orbiting objects to repair, sabotage, hijack, or simply collide with them.