ASATs are a constant threat for all satellites, but a major issue is the security of satellites that are crucial for the nuclear-armed countries’ early-warning systems. Some of them warn about the launch of what might be a nuclear missile, while others (e.g. within the USA’s Advanced Extremely High Frequency network) are for use in communications in the aftermath of a nuclear strike. Each costs north of a billion dollars, is the size of a small house, and any sign of them being threatened makes those who own them very, very twitchy.
