A Russian helicopter fought an unusual Ukrainian drone armed with heat-seeking missiles, war watchers say

• Ukraine used exploding drone boats to attack Russian naval assets on Monday.
• Footage and imagery from the attack appeared to show drones with an unusual adaptation.
• The unmanned systems could be seen armed with what were identified as heat-seeking missiles. 

Ukraine appears to be arming its naval drones with heat-seeking missiles to defend against air attacks, an unusual innovation for Kyiv's growing arsenal of explosive unmanned systems.