I'm a bit concerned about the unintended consequences that might come of this. I went looking to see if/how Russia might evade this price cap, discovered something called "dark" shipping. These are old ships, bought for relatively cheap - that don't seem to pass modern safety regs. They’d be passing through sensitive areas (notably, straits of Denmark, straits of Malacca, waters off Malaysia and Indonesia). What could possibly go wrong?

Also, at-sea oil transfers to disguise the origin of oil and at-sea holding vessels.

Current standard is that vessels over 60' be equipped with AIS (essentially something that broadcasts a ship's name, heading, and coordinates). My guess is that they're turning this off on a regular basis. There's already been one collision between one of these 'dark' vessels and a Maersk container ship (probably more - but that's all I could find). I saw nothing about AIS in reporting on that incident, BTW.

If you say the US should find and impound these ships, AFAICT the US Navy is no longer configured for this kind of mission - which would require swarms of destroyers and cruisers. Instead, we have 11 carrier groups, which are really good at power projection - but can't be everywhere.

Frankly, I have no idea what the best way forward might be - but we should be aware that this is heightening the risk of a disaster. Ignoring it won't make it go away.