[Goose]

BC, if Ukraine hit any oil tanker, there would be an outcry over the environmental aspect. 

But, if the US wanted to impose 200% tariffs on the countries whose flag these vessels fly, that might cause some rethinking

Doubt it. Indeed some of these flags of convenience would become more expensive. However many of the small nations involved in this practice have little export commerce with the US, and what little they do have is easily replaced. Liberia and Panama do have lots of commerce with the US, but many of the other alternative flags of convenience do not.

[Goose]

BC, if Ukraine hit any oil tanker, there would be an outcry over the environmental aspect. 

But, if the US wanted to impose 200% tariffs on the countries whose flag these vessels fly, that might cause some rethinking

Doubt it. Indeed some of these flags of convenience would become more expensive. However many of the small nations involved in this practice have little export commerce with the US, and what little they do have is easily replaced. Liberia and Panama do have lots of commerce with the US, but many of the other alternative flags of convenience do not.