Drones - small in size and often cheap - have the capacity to locate soldiers and ammunition supplies, drop bombs and provide better visuals of what is happening on the battlefield. And in the year since Russia invaded Ukraine they have become an integral part of the war, with both sides playing a game of 'cat and mouse' to see who can come up with the best technology and tactics. While Russia has far greater resources - both in terms of soldiers and equipment - Kyiv believes drone innovation is one area where it can begin to catch up with Moscow.