THE US, long opposed to green regulations in international shipping, was oddly AWOL in April 2025 when the big moment came.

Some 90% of Marpol Annex VI signatories, including China and Brazil, gave their assent to a last-minute compromise regulation to get shipping to net zero by or around 2050.

Saudi Arabia, which has led the group of petrostates in opposing anything green at the International Maritime Organization for years, raised all its usual objections to this new ‘Net-Zero Framework’, but was overruled.

Formal adoption of an IMO regulation six months after an approval is usually little more than rubber-stamping.

Supporters of shipping decarbonisation — including Lloyd’s List — dared to dream that maybe, just maybe, this time could be different.

We were wrong.

In a joint statement on October 10, 2025, US Secretary of State Marco Rubio, Energy Secretary Chris Wright and Transportation Secretary Sean Duffy warned the carbon tax would have “disastrous” economic consequences.

They said countries that voted for the NZF could see their ships blocked from US ports or subjected to added port fees. They even warned of sanctions on officials sponsoring “activist-driven climate policies that would burden American consumers”.

The US brought out its diplomatic big guns, in what an insider dryly noted was what happens when you manage to annoy three US cabinet secretaries in one fell swoop.

Its new-look IMO delegation arrived at the extraordinary MEPC meeting in October like a MAGA litigation A-Team ready for battle, showing from the outset a better grasp of the letter of IMO law than their opponents, and with no qualms about breaking it in spirit.

During sessions — which were not even really supposed to reopen debate on the major issues — the US treated every minute like a prosecutor’s opening speech.

Behind the scenes, Rubio called government officials and flag registries — mostly smaller countries economically dependent on the US — to threaten economic retaliation if they voted ‘Yes’ to the carbon price.

The biggest procedural blinder came on the Wednesday, when the US pushed for a last-minute rule change that would ensure the NZF would never enter into force, even if it passed the vote.

This tied up the EU27 and non-governmental organisations like the International Chamber of Shipping for the better part of two days, as they tried to spell out how catastrophic a change from “tacit acceptance” to “explicit acceptance” of Marpol amendments would be.

This would not only block any environment rules, they argued, but block anything the IMO could do — an existential threat to the UN organisation that is still just as potent today.

While the US team provided the bombast, Mohammad Ayoub of Saudi Arabia was the opposition’s more calculating leader.

Ayoub is climate policy specialist at the Saudi Ministry of Energy, and represents the Kingdom at the UNFCCC climate talks. His presence at the IMO signalled how seriously the petrostates took the threat of regulating shipping emissions.

Ayoub and his counterparts from the UAE, Russia, Iran and others had long argued that the NZF would hike trade costs, promote untested marine fuels and technologies, and fail to force a transition to net zero.

Before the meeting, the petrostates submitted techno-economic analyses arguing the proposed changes went beyond the legal scope of the Marpol Convention.

They questioned the framework’s governance and how its tax funding would be spent. (The US branded it a “global environmental slush fund.”)

Saudi Arabia said the NZF’s target trajectories for emissions reductions — known as Z factors — were determined “in 48 hours haphazardly” and more time was needed to consider their potential effects.

Breaking an international consensus is much easier than building one. The US/Saudi message sounded reasonable: just a little more time to build consensus, consider the evidence, and come up with something acceptable to all countries.

But since they offered no alternative plan to regulate shipping emissions, the result, in practice, was that the IMO has done — and will continue to do — nothing about decarbonisation.

The EU27 and others in the Yes camp had few answers in response to this wrecking crew.

The trouble was that behind their threats, the US and Saudi Arabia raised plenty of valid points. The NZF is essentially an empty shell of a regulation, with important details about how it would work yet to be filled in.

African states worried that the regulation would funnel cash from their continent to shipowners and tech firms in richer countries.

The framework was certainly rushed through at MEPC83, because the US and Saudi Arabia were so effective in blocking any discussion of how market-based measures should work up until that point.

Shipowner associations were cautiously supportive in public, but uneasy about it in private.

A group of big shipowners with large investments in liquefied natural gas, led by Maria Angelicoussis, added pressure on countries such as Greece and Cyprus to change sides, which paid off when the pair abstained from the vote to delay the adoption vote, in breach of EU rules.

The US and Saudi Arabia pushed hard, but in some cases they were pushing at an open door.

The two big petrostates sought to convince swing voters — especially those with big ship registries but little other economic or political power — that it was OK to vote ‘No’.

If adopted, the NZF was expected to curtail investments in LNG-powered ships and raise tens of billions for green research and development.

It was the culmination of decades of painstaking diplomatic work. It could even still pass a vote in 2026, but it’s hard to see that happening for the regulation as it’s written today.

Would it have proven the catalyst for ‘holy grail’ fuel options such as green ammonia and methanol? We can’t yet say. But it was the closest thing to binding global action on climate change the world has yet seen.

In blocking that possibility, at least for another year, the US and Saudi Arabia have changed the course of shipping’s green transition, and all the investments that stem from it.

This is the first appearance by Rubio and Ayoub in the Top 100.