Ukraine's army is leaning on a private company's satellites. That dependence is now under scrutiny. When Starlink faces disruption, soldiers feel it on the front line. Starlink belongs to SpaceX, the firm run by Elon Musk.

It was meant to solve a simple problem: billions of people lack reliable internet, and cables are often too costly or too difficult to lay in remote places. Roughly 10,000 small satellites now circle the Earth to fill that gap. They orbit about 550 kilometres up, far below the traditional internet satellites at 36,000 kilometres, so signals travel much faster. The satellites pass data to one another by laser, so they do not always need a direct link to a ground station.

Users need only a small terminal. Its electronically steered antenna tracks satellites overhead and feeds a nearby router. That simplicity explains the spread. Aid workers use it in disaster zones where networks have collapsed.