When satellites need bodyguards

Look up at a clear night sky and the stars are impossible to miss. Far harder to notice are the nearly 16,000 functioning satellites now circling the Earth, moving silently through the space between us and those distant points of light.

In little more than six decades, orbit has gone from an almost empty frontier to an environment filled with spacecraft on which governments, economies and militaries increasingly depend. That dependence is now changing the way states think about protecting what they have placed above the Earth.

Japan has given that shift one of its most striking expressions. Its Defense Ministry is considering the deployment of six “bodyguard satellites” by 2035: spacecraft whose purpose would be to help protect other Japanese satellites in orbit.

From support to target

Satellites have served military purposes since the Cold War, but their role has moved far beyond reconnaissance and early warning. Ukraine has demonstrated how satellite imagery can follow troop movements and contribute to targeting, while satellite communications connect forces across the battlefield.

The importance of such capabilities has also appeared in the Middle East. U.S. officials said Iran acquired high-resolution satellite imagery of an American base in Jordan from Chinese entities before a July 2026 missile strike that killed three U.S. troops, and said the imagery was connected to the attack.

As satellites have moved closer to the targeting process, denying an adversary access to them has acquired greater military value. Counterspace capabilities range from jamming and cyberattack to weapons capable of physically destroying a spacecraft. China’s destruction of Fengyun-1C in 2007 and Russia’s destruction of Cosmos 1408 in 2021 demonstrated the latter, while also producing large quantities of orbital debris.

The threat can also come from orbit itself. Rendezvous and proximity operations allow spacecraft to approach, inspect, service or dock with other satellites, but the same maneuvering capabilities can potentially support interference with them. The United States, China and Russia have all developed spacecraft capable of such operations.

It is this possibility that Japan’s proposed bodyguards are intended to confront.

Building the orbital bodyguard

Protecting a satellite begins with knowing what is moving around it. Japan has spent several years expanding its Space Domain Awareness (SDA) network, which tracks satellites and debris and seeks to determine the capabilities and intentions of suspicious spacecraft. The Defense Ministry plans to launch its first dedicated SDA satellite by the end of 2026 while also testing maneuverable spacecraft designed to respond autonomously to developments in orbit.

The next step is to bring that awareness closer to the satellite itself. In March, the ministry disclosed three research programs specifically aimed at monitoring and protecting Japanese spacecraft. One uses high-precision laser ranging to establish the distance of a potentially threatening object. Another places monitoring equipment onboard the satellite to provide early warning when an unidentified spacecraft approaches. A third is testing a grasping mechanism that would allow an auxiliary satellite to dock with another spacecraft for inspection or to help sustain its operation.

The proposed bodyguard satellites would add an active response to those capabilities. The spacecraft would be remotely controlled, use cameras to observe foreign satellites and debris, and maneuver to obstruct the course of a satellite attempting to approach a protected Japanese asset. A prototype could be launched as early as 2028 to test operations in geostationary orbit, around 36,000 kilometers above Earth, before a six-satellite system is established between 2033 and 2035.

The distinction between the existing programs and the proposed fleet remains important. Japan has already funded technologies for detecting, measuring and operating near other spacecraft. The six-satellite bodyguard system, however, is still under discussion for inclusion in the security documents Tokyo plans to revise by the end of 2026.

A growing club of orbital defenders

Japan is not alone in assigning spacecraft a protective role. In the United States, the function has already entered military doctrine. The U.S. Space Force’s 2025 Space Warfighting framework identifies “escort” as one of the forms of active space defense, defining it as the dedicated protection of friendly spacecraft through space-to-space capabilities. It distinguishes between point defense, focused on particular spacecraft, and area defense covering a wider region.

France is also moving toward an operational capability. An August 2026 update to its military programming law accelerated plans for action in geostationary orbit, replacing a previously planned single satellite with three “patrouilleurs-guetteurs,” or patrol-watch satellites, to be in orbit before the end of 2030. The first of these capabilities is scheduled to become operational in 2027. The same legislation places them within a wider expansion of French capabilities for space surveillance and action in and toward space.

As such missions move from monitoring toward active protection, they also raise a harder question: what rules govern how one military spacecraft may respond to another in orbit?

Rules for a crowded orbit

Military activity in orbit is not prohibited outright. The 1967 Outer Space Treaty bars states from placing nuclear weapons or other weapons of mass destruction in orbit and prohibits military bases, weapons tests and military maneuvers on the Moon and other celestial bodies. It does not impose an equivalent prohibition on military satellites or conventional weapons operating around Earth. The treaty also requires states to act with due regard for the interests of others and provides for consultations when an activity could cause potentially harmful interference with another state’s peaceful use of space.

Those provisions were written long before spacecraft could routinely maneuver around one another with the precision now possible. U.S. military operational lawyers identified a continuing lack of clear standards for determining when unfriendly activity in space crosses into armed conflict and what constitutes an “attack” in orbit. Rendezvous technology illustrates the problem particularly well: the same capabilities that allow a spacecraft to approach another for servicing, inspection or maintenance could also be used to grapple an adversary’s satellite without its consent.

The uncertainty extends beyond physical contact. There is no settled agreement over whether disabling a satellite without physically damaging it constitutes an “attack” under international humanitarian law. The International Committee of the Red Cross says loss of functionality can be enough, while narrower interpretations require physical damage or injury. This disagreement matters in a domain where jamming, cyber operations and other forms of interference can deprive a satellite of its function without destroying it.

Bodyguard satellites add another element to that problem because their purpose is to react before the protected spacecraft has necessarily been damaged. U.S. Space Force doctrine states that active space defense, including escort, rests on a determination of a “hostile act or demonstrated hostile intent” and requires near-real-time identification of a threat and characterization of an attack.

An approaching spacecraft may therefore be visible and precisely tracked while its intentions remain unclear. That ambiguity can delay attribution and a defensive response, potentially leaving a hostile spacecraft more time to complete its maneuver before its actions are clearly identified as a threat.

Japan’s proposed bodyguards therefore arrive at a moment when the technology for operating around other spacecraft is advancing faster than the rules governing encounters between them have been settled. Satellites have progressed from observing wars to becoming indispensable to their conduct. The satellite that once watched the battlefield from above may soon have another satellite watching over it.