A US aircraft carrier's passage through the Gulf is the latest demonstration of the superpower's enduring military presence in the Middle East aimed at reassuring allies, experts and officials say.
In a potent symbol of military might, the USS Abraham Lincoln carrier and its attendant warships cruised through the Strait of Hormuz this week.
The US military has taken action to emphasise its long-standing presence in a region where the US has deep strategic interests and partnerships.
The USS Abraham Lincoln's transit through the strait, which earlier this year was rocked by a string of attacks that have been widely blame on Iran -- accusations Tehran firmly denies -- was the first for a US carrier since April.
'Message of defiance'
For more than seven decades, the US has played an important role in the conflict-ridden region, serving in particular as a defender of Gulf monarchies against external threats, most notably Iran.
Since May, tensions in the Gulf have increased with attacks against tankers, followed by drone and missile strikes on key Saudi oil facilities. Iran was blamed, but denied involvement.
The US has so far avoided equivalent retaliation.
Sending the carrier through Hormuz "is certainly supposed to send a message of defiance and strength", said Andreas Krieg, a professor at King's College London.
The strait, which separates Iran and the UAE, is a chokepoint for a third of the world's seaborne oil. The shallow waterway is just 50 kilometres wide, making it a vulnerable shipping lane.
Maintaining a 'credible threat'
Despite US President Donald Trump's lack of enthusiasm for military involvement in the Middle East, the US still has some 60,000 troops in the region, including in Bahrain, which is home to the US Fifth Fleet.
The Pentagon said last month it will deploy thousands more troops to Saudi Arabia to protect its ally from "destabilising" Iranian actions, the first such deployment since US troops left the kingdom in 2003.
"It is almost certain that the US will not leave the Gulf. Even under Trump's policy, which decoupled Gulf security from the Iranian nuclear programme, a continued US presence in the region makes sense," saif security analyst Aleksandar Mitreski.
"The US... needs to maintain a credible threat to Iran," he said.
Earlier this month, the US led a naval exercise in the region involving more than 60 nations and shortly after, held a launch ceremony for a new maritime coalition.
An enduring commitment
"Our commitment to the region is not short-lived, it is enduring, and we will operate (here) as long as it is needed," US Navy Rear Admiral Alvin Holsey, commander of the newly formed coalition, said at the time.
Seasoned observers agree that the long engagement in the region, rich in historical links, essential energy resources and vast weapons contracts, cannot be easily broken.
"Trying to leave the Middle East is a little bit like Michael Corleone trying to leave the mafia," said former CIA director Gen. David Petraeus, referring to the protagonist of Mario Puzo's novel, The Godfather.
"You understand why that might be an objective, but it is virtually impossible," he said at a security conference in the UAE capital Abu Dhabi last month, to laughs from the crowd.
"You can try, but you are going to be called back in... In fact, there is no country that can replace us," Petraeus said.