Taken together, the available details describe a missile corvette turning back in a crowded, cabled waterway while at least one drone crossed Baltic airspace and allied aircraft stayed aloft without firing.
Finland's military has given few details of what happened. The incident appears to have taken place in a narrow stretch some distance from the Finnish coast.
The setting is sensitive. Defence officials are understood to have stressed to Kyiv that the gulf is a relatively narrow waterway used by oil tankers and civilian vessels.
Those officials are also understood to have noted that the same waters are home to subsea data cables.
The ship itself went back toward St Petersburg. Moscow rarely gives details of casualties or damage sustained by Russian navy ships, and none clarified the outcome.
Herem said one drone entered Estonian airspace briefly from Latvia and then headed toward Russia.
Nato aircraft based in the Baltic states were in the air at the time. Herem said it had not been considered safe for them to destroy the drones.
There were also unconfirmed reports of Russian combat helicopters being destroyed. Those reports stood apart from the limited official account of the ship.