Ukraine is destroying Russian warships using cheap remote-controlled sea drones, a major blow to Russia's military and its control of the Black Sea.

• Ukraine says its drones hit close to 200 Russian vessels in just three weeks in July.
• The drones cost around $1,000 each but are taking out large, expensive warships.
• Operators steer them from inside Ukraine, striking ships from a safe distance.
• The attacks embarrass Russia's navy, once seen as the far stronger force.

Outlook: Expect Ukraine to keep leaning on cheap drone strikes to chip away at Russia's fleet and loosen its grip on the Black Sea.