US blockade of Iranian ports explained by international law professor Al Gillespie
A New Zealand law professor breaks down the legality, risks, and geopolitical implications of Trump's naval blockade of Iran.
Summary
Host Chelsea speaks with University of Waikato International Law Professor Al Gillespie about the US blockade of Iranian ports declared by President Donald Trump. Gillespie explains that while a blockade of this kind is technically legal under international law, it carries enormous practical risks — including the threat of Iranian attacks on US and neutral vessels in the Strait of Hormuz, potential disruption to global oil supplies, and the danger of escalation to ground combat. He argues that Trump is correct on the principle of freedom of the seas but has backed himself into a corner by linking that principle to what Gillespie describes as an illegal war, causing NATO allies and other partners to distance themselves from the effort.
Key Takeaways
FULL TRANSCRIPT
What the blockade means and how it works
Host: The US blockade of Iranian ports has begun. President Donald Trump is warning any ships that try to disrupt US efforts will be eliminated. Earlier, Iran's parliament speaker said the country would not surrender under threats. Weekend peace talks between the US and Iran ended without resolution, with Trump blaming Iran for not being willing to end their nuclear ambitions. Vice President J.D. Vance has said it's up to Iran and the ball is in their court when it comes to peace talks. So what exactly is a blockade? Is it even legal? And what could it mean for the wider conversation? Today on The Front Page, University of Waikato International Law Professor Al Gillespie is with us to unpack the implications and explore what this move might really achieve. First off, Al, when we hear about a US blockade on Iranian ports, what does that actually mean?
Al Gillespie: What it means is that no vessels will be able to come from the Iranian ports through the Strait of Hormuz. And it also means that no vessels — including neutral vessels which aren't Iranian — can carry goods from Iran outside of the Strait of Hormuz. So that part of the coastline, and it's a large coastline, is completely stopped to trade for Iranian vessels and vessels trying to get to that part of the world.
Host: And so what differentiates a lawful blockade from an unlawful one in this context?
Al Gillespie: Well, there are a couple of things you've got to look at. To be lawful, it has to be declared, and it must make sure it does not stop certain goods — in particular, humanitarian goods or food. So you must always allow food into an area. And the second thing is you have to make sure that neutral vessels are able to still transit the area and still have freedom of the seas. And so for other boats going through the strait and going to Saudi Arabia, Kuwait, or Oman, they will be fine. It's only those that are going to Iran that will have problems.
Host: And how do you know which vessels are which?
Al Gillespie: Well, you will board the vessel. Every vessel will have search and seizure, whereby the American Navy will come on board and check its manifest — where the boat's been, what goods it contains, and where it's trying to go. And if they suspect that it's an Iranian vessel or a vessel carrying Iranian goods, then they will seize that boat and take it away and decide what to do with it.
Host: I can't imagine that Iranian vessels will be following all of the checks and balances and crossing the T's and dotting the I's. What ways can they make sure that it is an Iranian vessel?
Al Gillespie: Well, there will be a register and they'll be able to see what flag it flies. But that's the easy part. The hard part is when you've got vessels from other countries like China or Russia which decide to continue to trade with Iran and try to get the oil out. And America seizes one of their vessels — that's when it's going to get very sticky diplomatically, because the Russians or the Chinese or any other countries are going to say, "We've got freedom of trade." And America is going to say, "No, there's a blockade. We control the situation." This used to work very, very well in the 19th century. It doesn't work so well in the 21st century.
Host: Why is that?
Al Gillespie: Because the world is more complicated. It's more economically integrated and there's more exchange going on between these areas of the high seas and the territorial sea. So historically it was easier because you had fewer countries and fewer rules at play. Now what Trump's done is he's dredged up a rule from the 19th century, tried to update it to the 21st century, and he's going to hope that all other countries abide by it — but that will be difficult.
Risks to US vessels and crews
Host: How much danger does that put those crews on US vessels participating in this blockade?
Al Gillespie: For a blockade to be lawful, it has to be effective, which means that you have to have naval boats around the ports and around the waterways so that they can effectively control what they're trying to restrain. That means that American vessels are going to be in and around the Strait of Hormuz, in the Persian Gulf, in the Gulf of Oman — and they're going to be effectively in a war zone. This will be a high-risk situation because this is probably what Iran's been waiting for. Now they'll be able to deploy whatever weapons they've got that could hit the American vessels. Whether you're looking at sea mines, sea drones, fast attack boats, or even missiles, this is where the risk will come — not just for the American vessels trying to control the strait, but also for any neutral vessels. A lot of neutral vessels aren't going to feel safe because they know that Iran will be aiming at them.
And it's not really just an insurance issue, as Trump may have suggested. Yes, you can still get insurance for the strait for your vessel, but it's just more expensive now. The real issue is that people don't want to put their crews at risk. People don't want to be shot at, which is a reasonable human response. And also the economics of it — because even though you can get insurance, it will drive up the cost of the commodity that you're trying to sell. And so that's what this means for a country like New Zealand: we can continue to expect that the price of commodities, and oil in particular, will continue to increase, not get cheaper, in the foreseeable future.
If the blockade worked seamlessly — if Iran did not contest it — in theory the shipping would flow. But in reality, they are probably going to go for a knockout blow, where they try to sink an American vessel or try to sink some neutral vessels. And that will push the economic prices of all the commodities that go through the strait up.
Freedom of navigation and international law
Host: Does this US blockade risk breaching the broader principle of freedom of navigation under the UN Convention on the Law of the Sea?
Al Gillespie: In simple terms, the rules of blockade trump the law of the sea. But in theory, you can have a blockade on Iran while still having freedom of transit for all non-Iranian vessels and all vessels which don't trade with Iran. So in theory you've still got freedom of transit. In reality, you haven't — what you've got is a blocked waterway. But in theory they are different things and you can still have that freedom. Mr Trump will be trying to make countries say, "It's safe to go now, bring your vessels through." But a lot of countries are going to be saying, "We don't consider it safe, we're not going to do that."
The other thing Mr Trump will be trying to do is ask countries to help with the blockade. But for countries like ourselves, we've got to work out: do we support the blockade, or do we object to it? And so it's not just about having your military there — it's also about whether you agree with this at all, which is legal, but which is going to make your costs more expensive.
What a successful — or disastrous — blockade looks like
Host: What would a successful blockade look like?
Al Gillespie: That the Iranians are hemmed into the coastline, that there is no firing of missiles or attack boats or drones or sea mines, and that the traffic flows freely and gets back to a regulated speed and everyone is safe. A disastrous blockade is the exact opposite of that — the Americans try to control the seaway, the Iranians contest it. But then you've got one step worse than that: to protect the seaway, you've got to control the coastline, which would mean boots on the ground. Because that's often the only way historically that you can control the side you don't want deploying the mines, the drones, or the missiles. But if you put boots on the ground, then the whole complexion of this war would change very quickly. And you'd be playing right into Iran's hands as well, because that's exactly what it wants. This is the one chance they've got of levelling the playing field.
The superiority that America and Israel has over Iran right now is in technology when they're at 12,000 feet. But when they're on the ground — and remember, the streets around the coastal zones — it could quickly level up to a much more equal combat status.
The nuclear dimension
Host: What was the second point over? You said it was over nuclear.
Al Gillespie: It was over nuclear, yes. It's over the fact that they will never have a nuclear weapon. Iran will not have a nuclear weapon. And we agreed to a lot of things, but they didn't agree to that. And I think they will agree to it — I'm almost sure of it.
New Zealand's diplomatic and trade options
Host: What do you think New Zealand's likely options are for responding to this — diplomatically, politically, or in terms of just protecting Kiwi-flagged vessels in the area?
Al Gillespie: With Kiwi-flagged vessels, if there are Kiwi-flagged vessels out there, we would have to work out whether the government would encourage them to use the freedom of transit, knowing that the American Navy is backing it and trying to make it safe — that's the first thing. The second thing is whether we support the blockade or not. It's a legal thing that Mr Trump is doing. Even though the war is illegal, this method is legal — but we can still voice our opposition to it, because our foremost concern right now with this war is trying to get prices down and trying to get the goods to flow again. And having a blockade is probably not in New Zealand's best interests, but whether we voice that or not, I'm not sure.
Impact on global oil prices
Host: So how might this blockade affect global oil prices?
Al Gillespie: If Iran responds and takes the war back to America or targets the neutral vessels going through the waterway, it will become even more congested than it is now. At the moment, there's a trickle of boats going through. If the blockade is applied and Iran contests it, the trickle will stop. The other risk is that it won't just be with regard to the Strait of Hormuz — it'll also be with the Red Sea, because the Houthis, who Iran also controls, have a capability to expand their military capability in that ocean as well. And so right now we're looking at one strait being blocked, not two waterways. And that's the possibility if Iran decides to throw everything into making this as difficult as possible.
Was the blockade Trump's best option?
Host: I suppose this is a legal decision, so it is a legal blockade, and it is a high-risk one. But what other options did Trump have?
Al Gillespie: Trump's not wrong to be defending the freedom of the high seas — the freedom of the seas and the freedom of transit of vessels. And when they went to the negotiations in Pakistan, he was correct not to allow Iran to have that, because it was one of the things that they wanted — their ability to control the vessels. The problem is that this control that Iran has, and that it seeks, even though it's illegal under the law of the sea, is one of the few powers that Iran has right now. And it's linked to the war and the failure of the diplomacy to get to this point.
So even though Trump is right on freedom of the seas, he's wrong on the other matters. But the two of them are becoming overlapping. He knows he's got to open up the strait, but he hasn't got many other tools to do it. What I expect he's been trying to do is pressurise countries like France and Britain and NATO to be part of the blockade. And even though it's a lawful choice, these countries and groups are saying, "We're not going to get involved in the illegal war."
Other countries like China and Russia are delighted — because, one, Mr Trump's in a mess. And for Russia, the blockade means that their oil is now becoming very valuable and all the sanctions against them because of the Ukraine war have now been put in the waste paper basket. So having the blockade and Trump's continual mistakes suits Russia. It suits China. And the allies that Mr Trump has with NATO and countries like France and Britain are taking a step back because, even though he's not wrong about trying to open up the strait, because it's connected to an illegal war, they won't get involved.
New Zealand's trade relationship with the US
Host: Could taking any decision — whatever it may be, even symbolic support or criticism of the blockade — carry risks for New Zealand's trade relationships with the US?
Al Gillespie: Mr Trump does not take criticism at all well. And a lot of our policy has been trying not to offend Mr Trump. And so even though there are things which we strongly disagree with, if we say anything, we will say it in very nuanced language — which is a difficult position to be in, because many of the things he's doing right now are outrageous. But this principle in particular — the freedom of the oceans — is not outrageous. He is correct on this principle. The problem is that there's a tension between the freedom of the oceans and the illegal war, which is on the other side. But he's got no easy solution right now. His alternative, if he walks away, is that he gives Iran the victory that he feared to begin with. And not only would they have their nuclear ambitions uncontrolled, they would also control the waterway. And so he's really backed himself into a corner right now. It's for Iran to exploit this more than for America to open it up.
The prospect of ground troops
Host: So the next step of the war, if Trump were to continue, would be boots on the ground. But how likely is that when those boots would only be Israeli and US?
Al Gillespie: If the strait can't be opened up, if the blockade requires occupation of the coastal zone and requires boots on the ground, the next question is whose boots go in there. Because the last thing he will want is American boots, and so he will try to influence other countries to be part of his coalition. But right now, apart from Israel, all of the like-minded friends are staying very far away from Mr Trump. And the one group that might be sympathetic — such as the Kurds or some Iranian dissidents — will also be scared about trying to get their people organised in that area.
Is it possible? It is possible. And you can only look at historical examples like Gallipoli, whereby you try to force a strait, it doesn't work, you land your soldiers — and every Australian and Kiwi knows how badly that went.
Questions about Trump's judgment at home
Host: I've seen some former allies and advisors even questioning Trump back home, whether he's gotten increasingly unbalanced. I saw some describing him as a lunatic, another one as clearly insane. The White House has obviously rejected these statements, saying he's sharp and keeping his opponents on edge. I can imagine that's a pretty high threshold to get him out of office. But what's it like back at home on US soil for him?
Al Gillespie: The possibility of impeaching Mr Trump or using the 25th Amendment — you're going to need two-thirds of Congress to do that, and that is very unlikely. It's possible when you've had the congressional elections in November and there's a change in the House of Representatives and a change in the Senate, but you're going to need a two-thirds majority in both parts. And that does not exist now. It may exist in November, but that's the point at which you'd have him removed from office. Before that point, it's all just conjecture.
But if you used some of the language that Mr Trump uses, you would lose your job. Or if you posted images of yourself as a messiah, people would question your integrity. Yet he has lowered the standard of what we expect from someone of the highest office in the world. Yet there's nothing you can do — the only people who can do something about this are the Americans, and that will be in their election in November. But he still has many supporters as well, and so you've got to be careful who you listen to here. Because as much as there's a lot of concern about him — and I think that's legitimate — there's also a strong support base that believes he's doing the right thing.
Host: Thanks for joining us, Al.
Al Gillespie: You're welcome, Chelsea.