Last week, a UK-flagged tanker was seized by Iranian Revolutionary Guards, along with 23 crew members.
Coming shortly after British forces seized an Iranian vessel in Gibraltar, it was the latest incident in a series of spats between Iran and its rivals, including the US and Saudi Arabia: in the Strait of Hormuz, through which millions of barrels of oil pass every year, Iran has been accused of attacking civilian tankers.
While the country has been the focus of a "maximum pressure" policy by the US, President Trump has so far resisted overt aggression. But now, the US has proposed forming a naval force to secure the Strait of Hormuz.
So what’s going on? Are we teetering on the edge of World War Three? If there was fighting, what might it look like? What would be the UK's role? I asked some experts to try to find out.
Naysan Rafati, Iran Analyst at International Crisis Group
We're in a high stakes environment at the moment – one significant spark could set off a response. Raising the prospects of a US reaction would be anything that directly impacts their assets or personnel. This needn't necessarily be in the Strait of Hormuz: the US has held Iran responsible for incidents in Baghdad, Kabul and Yemen.
Right now, any action that one side considers as limited and meant to restore deterrence could end up leading to a counter response that leads to an escalatory ladder.
Iran consider themselves under siege more or less already. Their leadership talks about economic terrorism by the US, and 80 percent of their economy is under sanctions – I expect that will continue. We've also already seen cyber-attacks against Iran. They won't want to be seen to capitulate to US demands under duress, and have said that any attack against Iran itself would be responded to.
In terms of conventional military strengths in a confrontation, the US has, by every metric, escalation domination. Trump has indicated he has no interest in putting boots on the ground, so we're probably talking naval and aerial operations. There's no question that Iran would suffer significant losses if they ended up in a situation of direct military action with the US.
What the Iranians do have are missiles and local allies, proxy groups. It's entirely possible that an escalation with Iran would manifest across regional flash points.
Michael Stephens, Research Fellow for Middle East Studies at Royal United Services Institute
Iran have been ridiculously effective. They've ensured they are always a step ahead of us, that they are able to respond, don't look weak, and yet we're nowhere near where it looks like a war.
They know the line is a dead American serviceman. What Iran understands is that if they get into a military conflict with the US there is only one winner. So they don't get into a military conflict with the US. That's as simple as it is.
What is slightly problematic is that Trump made clear he was not interested in conflict. When you signal to an enemy you don't want to escalate, that means, in anything up to a war, Iran can dominate escalation. The moment it gets military, it's game over, because the Americans will just wipe them out.
The international maritime force is unlikely to be an offensive force; it will be designed to keep Iranian boats away from civilian shipping. The Iranians will not provoke a conflict with a US frigate.
If escalation occurred, the UK's role should be to lengthen the chain of escalation, putting in as many things as possible for the US wind around before getting to a war. We do need to avoid conflict, but if we use diplomacy and cyber penetration, those things are very effective.
With a new Prime Minister, this is a huge strain on a government that is distracted by Brexit. This crisis reminds us there is more to life than Brexit, and we have to be involved in these issues. We would have to go along with the US but make sure we are a constraining partner.
James Rogers, Director of the Global Britain Programme at the Henry Jackson Society
Under a new administration, the British will be keen to reset relations with US after the resignation of [former British ambassador to the US] Kim Darroch, and to seek a trade agreement. The UK must also respond in some way to show it can defend its interests. I imagine the government would be quite keen to be part of any maritime protection force to be sent to the Strait of Hormuz.
Military confrontation is a possibility, but a war is less likely at this stage. If Iranians fired on US or UK assets, especially manned, then that has the risk of escalation. Firing on multiple unmanned assets also raises the risk of escalation, and the US would be backed into a corner and forced to make some kind of response. Which could lead to military confrontation, which could lead to further escalation.
But we don't seem to be there yet, even though the US was contemplating it after their drone was shot down. I think escalation would be more likely to be greyer, using tactics such as a cyber strike or special forces operation – something that would cause harm to the regime, but less visible, and wouldn't allow for prospect of additional response on Tehran's part. It's not serious enough to warrant a stronger escalation.
If the US asked the UK for direct military assistance it could take a number of forms, such as for surveillance aircraft, intelligence or the use of regional military bases such as RAF Akrotiri in Cyprus.
Dr Simon Mabon, Director of the Richardson Institute and senior lecturer in International Relations at Lancaster University
It's pretty dangerous. Tensions are high and there are a number of different moving parts. Iran is incredibly marginalised and has a long history of what it sees as ostracisation and persecution from global politics. It has a long history of interference in its domestic affairs, dating back to the turn of the 20th century.
The big thing I worry about is the breakdown of diplomacy and an inability to open up backchannels, which means things can easily be misinterpreted and get out of hand accidentally, even if no one particularly wants a conflict. We need to rebuild trust.
There will be people working to keep dialogue open to prevent a conflict from happening, but in heightened security conditions there is a possibility of someone misreading something, or of rogue elements in the Trump or Iranian administrations who want a conflict.
If there was escalation and the UK followed the US, there would be much less inclination to work with the European powers to save the nuclear deal.
If the situation changed and there was a strike against Iran, that long standing idea of resistance against the US would very quickly be live again and could potentially unite other groups against the US. If things escalated and [Iran-aligned Lebanese Shia militia] Hezbollah get involved, there's a good chance Israel would get involved too. As well as in Gaza, Syria and Iraq, other long-marginalised groups that have some sort of relationships with Iran could well be mobilised, contingent on their capabilities and conditions.
Dr Andreas Krieg, lecturer at the School of Security Studies at King's College London and fellow at the Institute of Middle Eastern Studies
The situation is problematic because of heightened tensions, but we need to highlight that neither party to this crisis are willing to go to war over what's going on. What we see here is a fallout of withdrawal of the Americans from the nuclear deal, and the Iranians are responding to the US policy of maximum pressure with maximum resistance.
There's tit for tat pressure being responded to with counter pressure. Everything that's happening at the moment is below the threshold of war and will probably remain below the threshold of conventional war. But this is almost a war-like situation because very strategic infrastructure is being targeted by the Iranians in the Gulf.
Although I think diplomatic engagement is the right way forward, we need to uphold certain red lines. We need engage with Tehran and also need to deter the Revolutionary Guard from continuously harassing tankers, because that's a situation that's unbearable.
As well as the naval task force, an option to secure vessels in the Strait of Hormuz would be to put armed personnel on ships to deter attackers. While this would be under the threshold of war, it would still be a major escalation, and increases the likelihood of something going wrong.
The Iranians have so far shown restraint. They're not as risky in their behaviour as you might think. Everything is very calculated. A death is clearly a red line, and if that happened America would have to respond. If it came to that, I think we could see some limited strikes in retaliation against an Iranian base. But our partners in the Gulf are not immune in any way to retaliation from Iran, and they would be the easiest targets for the Iranians.
Interviews have been edited for length.
This article originally appeared on VICE UK.