Iran's Revolutionary Guards Corps seized a South Korean-flagged tanker in Gulf waters and detained its crew, Iranian media said on Monday, amid tensions between Tehran and Seoul over Iranian funds frozen in South Korean banks due to US sanctions.

Below are details about the Strait:

WHAT IS THE STRAIT OF HORMUZ?

The strait lies between Oman and Iran.

It links the Gulf north of it with the Gulf of Oman to the south and the Arabian Sea beyond.

It is 21 miles (33 km) wide at its narrowest point, with the shipping lane just two miles (three km) wide in either direction.

The UAE and Saudi Arabia have sought to find other routes to bypass the Strait, including building more oil pipelines.

WHY DOES IT MATTER?

Almost a fifth of the world's oil passes through the Strait - some 17.4 million barrels per day (bpd) versus consumption of about 100 million bpd in 2018, data from analytics firm Vortexa showed.

OPEC members Saudi Arabia, Iran, the UAE, Kuwait and Iraq export most of their crude via the Strait.

Qatar, the world's biggest liquefied natural gas (LNG) exporter, sends almost all of its LNG through the Strait.

POLITICAL TENSIONS

The United States has imposed sanctions on Iran aimed at halting its oil exports.

Iran has threatened to disrupt oil shipments through the Strait of Hormuz if the United States tries to strangle its economy.

The US Fifth Fleet, based in Bahrain, is tasked with protecting commercial shipping in the area.

MAJOR PAST INCIDENTS

During the 1980-1988 Iran-Iraq war, the two sides sought to disrupt each other's oil exports in what was known as the Tanker War.

In July 1988, the US warship Vincennes shot down an Iranian airliner, killing all 290 aboard, in what Washington said was an accident and Tehran said was a deliberate attack.

In early 2008, the United States said Iranian vessels threatened three US Navy ships in the Strait.

In July 2010, Japanese oil tanker M Star was attacked in the Strait by a militant group called Abdullah Azzam Brigades linked to al Qaeda claiming responsibility.

In January 2012, Iran threatened to block the Strait in retaliation for US and European sanctions that targeted its oil revenue in an attempt to stop Tehran's nuclear programme.

In May 2015, Iranian ships seized a container ship in the Strait and fired shots at a Singapore-flagged tanker which it said damaged an Iranian oil platform.

In July 2018, President Hassan Rouhani hinted Iran could disrupt oil trade through the Strait in response to US calls to reduce Iran's oil exports to zero.

In May 2019, four vessels - including two Saudi oil tankers - were attacked off the UAE coast near Fujairah, one of the world's largest bunkering hubs, just outside the Strait of Hormuz.

In January 2021, Iran seized a South Korean-flagged tanker in Gulf waters and detained its crew.