Every night the mosquito-like whine of smugglers’ speedboats used to sing across the busy Strait of Hormuz.

But since Iran and the west have been locked in a potentially deadly standoff, the steady flow of contraband goods between Iran and Khasab, in Oman, has slowed to a near halt.

It is just one of the many changes fishermen and dhow ship owners in the port, located on the tip of the strait, say they have noticed as the region has hurtled towards an all-out conflict.

From their ports, they watch with concern the rapid build-up of Iranian patrol boats and western warships, which has increased dramatically since Iran seized British-flagged tanker Stena Impero last month in one of the world’s busiest waterways.

The strategic passage, which carries 20 per cent of the world’s oil supplies, is now so packed with military hardware, diplomats fear a single miscalculation or human error could result in a major incident like a plane being shot down.

Even a brief flare-up could turn into a potentially devastating stranglehold on the global economy if it halted traffic in the waterway.

Locals like Faisal, a fisherman from Kerala, fear they are just one diplomatic mistake from an armed conflict on their doorstep.

“There has been a huge spike in ship movements since the troubles started around three months ago and we are concerned with what this means,” he tells The Independent, watching military vessels crowd Khasab’s main port behind him.

In the distance, the silhouettes of tankers heading towards the strait cut a string of rectangles into the horizon.

“The number of Iranian boats patrolling, also the British and American warships, is not normal,” he continues, as he watches the tankers.

Even the decades-old smuggling of contraband goods – like cigarettes, alcohol and mobile phones – to Iran from the United Arab Emirates and Oman, has all but stopped, which is a telling sign, fellow Omani fisherman Saleh adds.

“We just don’t know how this is going to play out.”

Oman and its neighbour the UAE, both with ports that flank the strait, are arguably the two countries most at the mercy of this regional tinderbox, and yet have been the quietest as the conflict has unfolded.

It is telling that Muscat refused an urgent request from London to confirm that the Iranians had seized the Stena Impero in Omani waters, not international waters, as Tehran claimed.

This is despite the fact it was a major breach of sovereignty.

This is largely because Oman, nicknamed the “Switzerland of the Middle East” has prided itself on being a regional mediator, by maintaining strong ties with Iran, the west and the Sunni-Arab Gulf.

It has refused to join armed coalitions fighting wars in the region, to the fury of its allies.

At the request of the British, however, Oman’s foreign minister, Yusuf bin Alawi bin Abdullah, agreed to come back from annual leave during the crisis and fly to Iran where, according to sources briefed on the matter, he returned with message of a “tanker-for-a-tanker deal” for London.

Tehran allegedly proposed that Stena Impero would be freed if the British ensured the release of Grace 1, an Iranian supertanker, holding some 2.1 million barrels of crude oil, which was seized off the coast of Gibraltar a few weeks before by the royal marines on suspicion of sending its cargo to Syria.

To the apparent surprise of Muscat, it was initially rejected by London on the grounds that the Grace 1 was legally detained, and the Stena Impero was not.

Nevertheless, Gibraltar released the tanker last week saying it had been assured the vessel would not unload in Syria, in the first sign of a possible scale-down.

A helicopter takes off from the USS Boxer as it passes through the strait (Reuters) (REUTERS)

On Sunday, the recently renamed Adrian Darya 1 had set course for Kalamata, Greece. It remains to be seen if the Stena Impero will follow suit.

But despite the apparent successes of Oman’s negotiations, analysts in the country believe that Muscat, the west’s only conduit to Iran, has reached the “limit” of what it should permit from its neighbour Iran.

“Iran is taking full control of the strait, but Oman isn’t talking about it at all,” Dr Abdullah al-Ghailani, an Omani strategist based in Muscat tells The Independent.

“I’m not saying we have to be tough on Iran, but we legally have the right to express the tanker was seized in our waters,” he adds.

He says that many were angry that Muscat had gained very little from its seemingly tireless shuttle diplomacy, while it was on the verge of being dragged into conflict for trying to befriend all sides.

I am concerned the situation in Hormuz would force Oman to take sides Ahmed Ali al-Mukhaini, independent researcher

“If you have all of this power why don’t you use it properly to serve the country’s interests? The question is what are we getting out of this as a country?

“There is no free lunch. What are the benefits for us?”

Ahmed Ali al-Mukhaini, an independent political researcher and former assistant secretary-general for the Omani Shura Council, says that if it was not for Oman’s diplomacy “there would be more chaos in the region” and possibly war over the strait.

“It’s a dangerous position to be in... I am concerned the situation in Hormuz would force Oman to take sides.”

Omani officials notably declined to comment.

The UAE, whose own port in Fujairah was attacked in May, has remained similarly quiet.

The US, Saudi Arabia and Israel have publicly accused Iran of being behind the string of explosions that hit four oil tankers off the Emirati coast, but the UAE, fearing an escalation, has stopped short of pointing the finger of blame.

In Abu Dhabi, Emirati officials have declined to say more than an unknown “state actor” was responsible, even when repeatedly pushed in interviews.

The UAE military has also denied a recent drawdown of their troops along the southwest of Yemen was anything to do with tensions in the strait – or a desire to sweeten Iran.

Abu Dhabi is part of a Saudi-led coalition fighting Iran’s allies the Houthis in Yemen, and so less military tension with the rebels will translate into less confrontation with Tehran.

But a senior military official told The Independent the unilateral action was decided months before the tanker debacle erupted.

“The drawdown aims to give [peace] negotiations a chance to succeed, it is an unreciprocated confidence-building measure,” the official added.

However, British and Omani sources pointed out in interviews with The Independent that the UAE needs to bring back its portable Patriot missile batteries, originally deployed to Aden to ward against airstrikes.

The number of Iranian boats patrolling, also the British and American warships, is not normal Faisal, fisherman

The missiles are needed to protect the home front, not just against a potential conflict in the strait, but possible drone attacks from the Houthis on its airports.

Emirati officials have privately admitted to an increase in security patrols near the strait. They know that any war over the waterway will not be limited to the sea.

However, Jaber Al Lamki, executive director of strategic communications at the UAE’s National Media Council, told The Independent: “It was business as usual at the Fujairah port.”

“In all our ports from Abu Dhabi to Fujairah we have seen no impact in terms of slowing down projects or vessel movement. But this is a serious threat,” he added.

“The Strait of Hormuz is an important vein for the world economy. No one is for escalation and we are very cautious.”

The region, for now, remains on tenterhooks.

Last week, the HMS Kent sailed to the area to relieve another British ship, the Duncan, already working in the region as part of a US-led mission protecting commercial vessels that has upset Iran. Poland is mulling joining the initiative.

HMS Montrose accompanies the Stena Important and the Sea Ploeg in the Gulf last month (PA)

Then on Friday, the US made a last-ditch effort to try to stop Gibraltar releasing the Grace 1, unsealing a warrant to seize the supertanker and its cargo, citing violations of US sanctions, as well as money laundering and terrorism statutes.

US officials said that oil aboard the ship was worth some $130 million and was destined fora terror organisation, claiming the Iran’s Revolutionary Guards are the ship's true owners through a network of front companies. Gibraltar said it could not comply with that request because it was bound by EU law.

Iran lashed back saying any American attempt to seize the tanker would have "heavy consequences"

Foreign Ministry spokesman Abbas Mousavi issued a threat saying, “Such an action, and even the talk of it ... would endanger shipping safety in open seas."

Until these tensions in the strait are resolved, Oman and the UAE remain exposed.

Back in Khasab, the tension is palpable when the conversation returns to the situation in the strait.

Many decline to speak fearing backlash from the authorities, and those that do, ask only their first name be used.

“We just don’t know,” says Ali, a fishermen in a speedboat with the main port behind him.