What are 'kamikaze drones'?
- Believed to include an Iranian-supplied weapon called the Shahed-136
- These drones loiter above a target before attacking
- Packed with explosives which detonate upon impact, destroying the drone
- Often sent in waves and difficult to spot on radar
- The US said Iran planned to send hundreds to Russia, costing just $20,000 (£17,800) each
- Ukraine has also used 'kamikaze drones' - including the US-made Switchblade model
