The US assesses that China's push to develop capabilities to "deny, exploit or hijack" enemy satellites is a core part of its goal to control information, which Beijing considers to be a key "war-fighting domain."

The CIA-marked document, which was issued this year and has been reviewed by the Financial Times, was one of the dozens allegedly shared by a 21-year-old US Air Guardsman in the most significant American intelligence disclosures in more than a decade. A cyber capability of this nature would far exceed anything Russia has deployed in Ukraine, where electronic warfare teams have taken a brute-force approach with little effect.

These attacks, first developed in the 1980s, attempt to drown out signals between low-orbit SpaceX satellites and their on-ground terminals by broadcasting on similar frequencies from truck-borne jamming systems such as the Tirada-2.

China's more ambitious cyber attacks aim to mimic the signals that enemy satellites receive from their operators, tricking them into either being taken over completely or malfunctioning during crucial moments in combat. The classified US document said this cyber capability would allow China "to seize control of a satellite, rendering it ineffective to support communications, weapons, or intelligence, surveillance, and reconnaissance systems." The US has never disclosed whether it has similar capabilities.

Taiwan, which has taken note of how indispensable satellite communications have been to the Ukrainian military, is seeking to build out communications infrastructure that can survive an attack from China. It is courting investors to establish its own satellite provider, while experimenting with non-geostationary satellite receivers in 700 locations around Taiwan to guarantee bandwidth in the event of war or disasters.

China's wants to knock out satellites' ability to communicate with each other, to relay signals and orders to weapons systems, or to send back visual and intercepted electronic data.