Al Jazeera: The Strait of Hormuz is a critical waterway to the world for Middle East oil and gas producers. Saudi Arabia, Kuwait, Iraq and Iran send tankers full of crude to clients mostly in Asia. It is also Qatar's main export corridor as the world's biggest producer of gas.

About a fifth of the world's crude passes through the narrow strait between Oman and Iran. After the United States pulled waivers for nations trading with Iran, a string of alleged attacks on tankers and drone attacks on pipelines have increased tensions.

To add to the mix, Washington ordered some non-essential embassy staff in Baghdad to leave and has sent a US attack group into the region.

The Americans are sending the Iranians "a mixed message at best", explains Al Jazeera's defence analyst Alex Gatopoulus. "It's highly unusual that there isn't an aircraft carrier in the region ... but the announcement that they're sending bombers and aircraft carriers sounds like it's a ramp-up in capabilities, but actually, it's business as usual."

"What has changed is the rhetoric. And the rhetoric is far more bellicose than it used to be. And when you have a load of increased tension, a load of military hardware in the region, the propensity for a mistake or an accident or something intentional or otherwise that will get us into a general conflict is much higher."

With Washington ratcheting up the pressure on Tehran, the oil markets appear to be relaxed, according to Giacomo Luciani, an expert of geopolitical energy from the Graduate Institute in Geneva.

"The market is relaxed because it's not clear what's going to happen and there's significant reserves of oil in case of unintended consequences," says Luciani. "People that are looking at this situation see an American administration that's blowing hot and cold on alternate days. I personally don't believe that President Trump is interested in going to war. He's letting his security adviser threaten - hoping that this will speed up a cave in on the part of Iran. But I don't think Iran will cave in."

"Closing the Strait is not very easy, and secondly, it's not necessary because tankers can be attacked anywhere in the Gulf," says Luciani.

"This has been attempted in the past during the Iran-Iraq war, and it has not succeeded. There's not been a serious disruption of the flow of oil out of the Gulf and I don't think there would be a serious disruption in this case. That said, it's always possible that things evolve beyond the intention of the players because sometimes you go to war by accident, and in that case, it's very difficult to predict what might happen."