The collision of a Russian fighter jet with a US MQ-9 Reaper drone over the Black Sea has raised fears of an escalation in the Ukraine conflict. Close encounters between western and Russian aircraft are not unusual, but the incident on Tuesday raises the stakes because it led to US officials having to crash land the drone into the sea.
The use of drones, or unmanned aerial vehicles (UAV), in and around war zones has been going on for decades. This is what we know about the MQ-9 Reaper and how it is traditionally deployed:
