The legal grounds: The oil was shipped by a US company in violation of US law. American companies can't do business with an organisation that the US government has designated as a terrorist organisation. Thus American authorities siezed the ship and its cargo.

So...will they seize the companies assets and arrest the CEO for violating the sanctions?

Because that's how you stop this shit.

There is a lot of misreporting and misunderstanding about this. OFAC (Office of Foreign Asset Control) exists within Treasury and is responsible for enforcing sanctions usually created by executive order ("EO"), or very rarely, Congress. EOs and OFAC interpretation are very specific: some sanctions, such as the ones on the export of Iranian crude/products, are explicitly extraterritorial. Meaning, the US reserves the right to come after you no matter what country you are a citizen of or where you company is domiciled. It's very rare for them to try this one anyone who doesn't have US nexus since there is not much practically speaking they can do, but they could in theory. OFAC has, no pun intended, FAQs for all of this easily found at their site.

Now, this case was extra stupid. Oaktree is the single biggest PE investor in shipping, going in heavy starting a bit before the financial crash and going in really big with Eagle Bulk c. 2012 or so. Oaktree is, as stated, a US company, but that wasn't the main reason: they did this transaction in USD. Which was stupid, but having met the bastards at Empire a few times, I can say they are not the brightest bunch (as as far as I understand they are doing most of this kind of work in EUR with some shady banks nowadays anyway). Anyway any transaction in USD goes through the SWIFT system (which is why kicking Russia out of it was such a massive deal). This means there was simply no way this was not going to get eventually scanned since banks have repurposed their AML programs into sanctions programs or subscribe to sanctions-specific services like PoleStar's PupleTrac (what my company uses) or Windward or Lloyd's, etc. Now the dirty secret is that the banks don't really understand movement data that well, but Empires has done this (and Venezuela) so often for so long, someone at Treasury probably said, "OK, since we got Oaktree all up in this, let's make an example of of these guys to scare others away from these trades."

[spoiler alert: it did not scare others away from these trades and most folks estimate there are about 1,000 large tankers that form a so called "Dark Fleet" trading in Iran, Venezuela, and now Russia since both crude and product have broken the price cap at all Russian export locations. You cam make about 40% more shipping such cargos than legal ones.]

Anyway, I digress, The the point is that OFAC doesn't care if you have US nexus; it just makes you easier to catch if you do. Source: I am the head of credit and compliance for a large oil company that works closely with the shipping industry.

They could at least give Iran back their oil. This is like when cops steal your jewelry and claim civil forfeiture.

US navy commiting piracy on the open seas because they're the only substantial naval force that exists globally

Seriously though, they do this to Argentina too lmao.

So much for free trade

You can tell from the comments in this post that Americans are immune to propaganda.

This is egregious big government overreach impeding business and free trade

I’m gonna take a break while the bots and state department shills get their talking points worked out; so they can explain and justify how this is legal by international standards.

ITT: "It's ok when we do it."

I think the proper word here is "liberated"

So privateer is a legitimate profession again?

And we wonder why they hate us.