At least for power cables, the point is Lithuanian/Latvian/Estonian grids. Currently they're still connected to Russian grids and frequency is controlled by Rus

At least for power cables, the point is Lithuanian/Latvian/Estonian grids. Currently they're still connected to Russian grids and frequency is controlled by Russians. But this is about to end on February 8th. On this day Lithuanian/Latvian/Estonian grids should completely disconnect from the soviet-era grids network and start keeping frequency on their own synchronised with central european grids.