With the increasing militarization of space, there have been a number of efforts to find an international agreement to create controls on the use of space weaponry. But there’s a problem: How do you create a meaningful framework for a treaty against space weapons if no one defines them the same way?

It’s an issue that Todd Harrison of the Center for Strategic and International Studies tackles in a new paper, first viewed by C4ISRNET, in which he attempts to create a taxonomy of space weapons.

The report comes at a time when a number of countries, including Japan, France, South Korea and the United States, are expanding or standing up military organizations specifically focused on space, with officials in those nations hinting at, if not outright declaring, the need to expand their respective space weapon capabilities.

While the Partial Test Ban Treaty and the Outer Space Treaty place limits on the weaponization of space, Harrison argues there is no real consensus on what the weaponization of space means — even as it is becoming impossible to deny that a number of nations already have space weapons.

“To get to a consensus definition on what counts as a space weapon and what doesn’t, you would need a treaty mechanism that is widely accepted,” Harrison said. “The odds of that happening are slim to none. So I think in a practical sense, countries will continue to define space weapons to mean whatever they want it to mean to suit their own purposes. And we’re going to have to navigate through that, in terms of communicating with allies and partners and communicating with the public.

“People are still saying we shouldn’t militarize or weaponize space. When you go through the framework, and you look at what countries have already done, I think you have to stop and say it’s already been weaponized. And it’s been that way for decades.”

The report organizes space-based weapons into six categories, featuring kinetic and non-kinetic versions of Earth-to-space, space-to-space and space-to-Earth systems. Of those, three categories have been proven through testing, deployment or operational use:

  • Earth-to-space kinetic: Physical systems launched from Earth, such as the anti-satellite missile test by India in 2019. Such weapons risk leaving behind fields of space debris, and they could be conventional or, in theory, nuclear warheads. The United States, Russia, China and India have shown such capability, with the U.S. and Russia having performed nuclear tests in space in the 1960s. Russia tested such a capability as recently as April.
  • Earth-to-space non-kinetic: Jammers, laser dazzlers or cyberattacks launched from Earth, upward. The effects can vary wildly, but overall the goal is to interfere, temporarily or permanently, with satellite capability. Many nations have this capability, including the U.S., Russia, China and Iran.
  • Space-to-space kinetic: Satellites physically intercepting other satellites to disrupt or destroy them, or weapons put specifically in space for this purpose. Debris is once again an issue here, as is the potential for use of a nuclear weapon, which could have fallout on a number of systems. The Soviet Union repeatedly tested co-orbital, kinetic anti-satellite weapons during the Cold War.
  • Space-to-space non-kinetic: A satellite is placed into orbit and uses non-kinetic, high-powered microwaves, jammers or some other means to disrupt another space-based system. There are no open-source cases of such a system being used, though Harrison notes it might be hard for outside observers to tell if it happened; France directly accused Russia of performing this kind of action in 2018, in what Paris described as an attempt to intercept military communications.
  • Space-to-Earth kinetic: A classic of science fiction, the ability to bombard a terrestrial target from space would give a true upper hand to whatever nation perfected it. Damage can be inflicted using the kinetic energy of the weapon itself (such as dropping a bunch of rods off a satellite and letting them build power during descent), or a warhead could be deployed on a reentry vehicle. The U.S. military has contemplated it in the past, but there are no open-source examples of such a system being tested.
  • Space-to-space non-kinetic: A system that could target down, whether through jamming of signals or through targeting spacecraft or ballistic missiles. The U.S. has talked about a desire for space-based laser systems for missile defense, but there are no open-source examples of such a system being used.

Harrison does not include all counter-space capabilities in his framework, specifically excluding weapons that are based on Earth and have an impact there.

“A form of a counter-space weapon, something used to disrupt or degrade our space systems, could be a sea-launched cruise missile launched at a ground station,” Harrison explained. “That could disrupt our use of space. I wouldn’t call that a space weapon, though, because it never goes into space.”

Broadly speaking, expect the development and deployment of space weapons to continue in the near future, Harrison said, but with an emphasis on those capabilities being used for defensive measures only — even though, he noted, “the same system can be used in another capacity.”

Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.

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