Russia’s grip on its gateway to the Black Sea is slipping after a series of Ukrainian attacks forced Moscow to suspend traffic through the key waterway this week, limiting the Kremlin’s ability to trade with the rest of the world.

The development marks a major reversal of fortunes for Russia as the Azov Sea was for years out of Kyiv’s reach, providing Russia with a convenient staging ground for attacks against Ukraine and linking vast swaths of southern Russia with the world’s oceans.

But recent advances in Ukraine’s drone program have changed this. Robert Brovdi, the commander of Ukraine’s ‌drone forces, said on Wednesday that Kyiv had hit 116 Russian vessels in the Sea of Azov in just the past nine days – a sharp increase.

Previously, strikes against Russian ships were mostly limited to the shadow fleet and military vessels. CNN cannot independently verify Brovdi’s claim, but videos of some of the recent strikes shared by Ukrainian officials show direct hits.

The relentless attacks have forced Russia to suspend traffic through the Azov Sea by shutting down the two chokepoints in its corners: the Don-Azov Channel, which connects the sea to inland waterways, and the Kerch Strait, which links it to the Black Sea.