Snake Island, or Zmiinyi Island, is only about a square kilometre in size, but holds great strategic value.
The heroics of outgunned Ukrainian defenders on the island at the start of the war grabbed world headlines when they defied a Russian warship’s demand to surrender.
The past few days have seen fighting intensify for control of the island, western experts said.
“If Russia consolidates its position on Zmiinyi Island with strategic air defence and coastal defence cruise missiles, they could dominate the north-western Black Sea,” the UK Ministry of Defence tweeted on Wednesday.
Following the loss of the Russian warship Moskva last month and the Russian Navy pulling back to Crimea, its resupply vessels have minimum protection from Ukrainian attacks, the ministry said.
Defenders of Ukrainian stronghold continue to repel attacks
It also said Ukrainian troops had “successfully struck Russian air defences and resupply vessels with Bayraktar drones“, produced by Turkey.
The incident was supported by a satellite image taken over Snake Island by Planet Labs PBC, showing thick black smoke rising from it last Friday.
If Russian troops on Snake Island install long-range air-defence systems, they will control the sea, land and air in the north-west part of the Black Sea and in the south of Ukraine.
Island a symbol of resistance
When the war started on February 24, the Ukrainian defenders of Snake Island were urged to surrender by the Russian missile cruiser Moskva or face bombardment.
According to a purported audio exchange, one of the Ukrainian troops responded with: “Russian warship, go f— yourself”.
After reports all the soldiers had been killed by the Russians, the Ukrainian military said they had survived and only surrendered after running out of ammunition.
In April, the Moskva – the Russian Navy’s Black Sea flagship – was sunk by a Ukrainian missile.
Neighbours worried by Black Sea conflict
The fighting on Snake Island has neighbouring countries worried, notably NATO member Romania which is only about 60km away.
This week, US special forces and other NATO troops have been holding military drills in the Black Sea amid concern of the Ukraine conflict widening.
They are part of the Trojan Footprint exercise, which involves 30 nations and more than 3300 special and conventional forces.