i suppose these ships only use Soviet / Russian ports, and mostly don't operate in high seas. Icebreakers do operate in high seas, but getting close to them is a bit hard due to ice and polar weather.
The more interesting example is NS Savannah [1], which indeed crossed oceans unattended, and was accepted at European ports.
The more interesting example is NS Savannah [1], which indeed crossed oceans unattended, and was accepted at European ports.
[1]: https://en.m.wikipedia.org/wiki/NS_Savannah