Russian President Vladimir Putin ordered his military to prepare options for retaliation against Ukraine on Friday after Moscow accused Kyiv of what it described as a deliberate drone strike on a college in the town of Starobilsk.

Russia launched waves of deadly airborne attacks across eastern regions of Ukraine which responded with retaliatory drone strikes into southern Russia.

One wave of strikes hit a Russian drone pilot training camp, killing at least 65 cadets and an instructor, Ukraine claims.