Ukraine just proved its sea drones are a huge threat to Russia's navy. An expert says this may only be the start.

• Ukraine attacked a Russian warship using a sea drone on Friday, videos showed.
• The country is focusing on building bigger and more powerful sea drones, an expert tells Insider.

Ukraine this morning used a sea drone to attack a Russian warship in the Black Sea, videos circulating on social media showed.

The attack on the vessel Olenegorsky Gornyak at the Russian port of Novorossiysk was carried out by a drone with about 450 kilograms of TNT, a Ukrainian source told CNN.

But this may only be the start. Stephen Wright, a drone-technology developer, told Insider that Ukraine was preparing to step up its attacks on the Russian Black Sea fleet with larger, more powerful drones.

In dashcam footage tweeted Friday by Anton Gerashchenko, an advisor to the minister of internal affairs in Ukraine, a drone is seen heading straight toward the warship before slamming into its side.

Even though Russia claimed it thwarted the attack, additional footage taken later showed the ship was badly damaged. Ukrainian intelligence services claimed they put it out of action.

Wright told Insider that the drone looked similar to a new naval drone that Ukraine revealed to CNN last week, which was described as being faster than anything in the Black Sea and capable of hitting targets 500 miles away.

Since launching one of its first large-scale drone attacks on the Russian-occupied Sevastopol Naval Base last October, the sea drones that Ukraine is designing were "actually getting bigger," he added.

"Why have they got bigger? Obviously, to get more explosives on board," Wright said, adding that Ukraine "would clearly like" to take out another target like the Moskva — the flagship of the Russian Navy's Black Sea Fleet, which sank in April last year after it was hit by Ukrainian missiles.

"I mean, that's clearly where they're going. They want to take out one of these," Wright said.

He said that 450 kilograms of TNT was a "huge amount" for a drone to carry: "To put it in context, estimates for the explosives being carried by the airborne strikes on Moscow are in the 5-10kg range."

A Ukrainian sea drone was also used last month to successfully damage the Kerch Bridge, CNN reported. The bridge was a key supply route between Russia and Crimea, which was annexed by Moscow in 2014.

Correction: August 4, 2023 — An earlier version of this story misspelled the name of the Russian warship that was attacked by the Ukrainian sea drone. It was Olenegorsky Gornyak.