A U.S. aircraft carrier ordered by the White House to rapidly deploy to the Mideast over a perceived threat from Iran remains outside of the Persian Gulf, so far avoiding any confrontation with Iranian Revolutionary Guard forces amid efforts to deescalate tensions between Tehran and Washington.

Officers aboard the USS Abraham Lincoln repeatedly told The Associated Press on Monday they could respond rapidly to any regional threat from their position, at the time some 320 kilometres (200 miles) off the eastern coast of Oman in the Arabian Sea.

However, after decades of American aircraft carriers sailing through the Strait of Hormuz, the narrow mouth of the Persian Gulf through which a third of all oil traded at sea passes, the U.S. Navy's decision to keep the Lincoln away is striking.

"You don't want to inadvertently escalate something," Capt. Putnam Browne, the commanding officer of the Lincoln, told the AP.

The White House in May deployed the Lincoln and B-52 bombers to the Persian Gulf. The U.S. also plans to send 900 additional troops to the Mideast and extend the stay of another 600 as tens of thousands of others also are on the ground across the region.

The crisis takes root in President Donald Trump's withdrawal last year of the U.S. from the 2015 nuclear deal between Tehran and world powers that capped Iran's uranium enrichment activities in return for lifting sanctions. Washington subsequently re-imposed sanctions on Iran, sending its economy into freefall.

Trump has argued that the deal failed to sufficiently curb Iran's ability to develop nuclear weapons and ballistic missiles, or halt its support for militias in the Mideast.

But amid the escalation, the U.S. alleges without offering evidence that four oil tankers off the coast of the United Arab Emirates were attacked with limpet mines. Meanwhile, Yemen's Iranian-backed Houthi rebels have launched co-ordinated drone attacks on Saudi Arabia.

The U.S. itself has made a point to show its arsenal in the region. On Sunday, the U.S. Air Force announced a B-52 conducted a training exercise with the Lincoln that included "simulated strike operations."

That came as Monday marked the 30th anniversary of the death of Ayatollah Ruhollah Khomeini, the founder of Iran's Islamic Republic. Thousands in Iran commemorate Khomeini's death by visiting his golden shrine south of Tehran. This year, Iranian military officials reportedly plan to guard it with HAWK surface-to-air missiles, the same kind the U.S. delivered to the Islamic Republic in the Iran-Contra scandal.

However, in recent days, the Trump administration has stressed it is ready to speak to the Iranians without preconditions. Iran in turn has demanded the U.S. show it respect.

Though officials repeatedly declined to discuss it, keeping the Lincoln out of the Strait of Hormuz and Persian Gulf helps to de-escalate the situation. Transits through the strait, which at its narrowest point is just 33 kilometres (21 miles) wide, often see the paramilitary Revolutionary Guard's naval forces shadow American warships. They've also run snap missile launches, fired machine-guns and flown drones over American carriers.

To Iran, which shares the strait with Oman, they view the American naval presence akin to Iranian forces sailing into the Gulf of Mexico. But the U.S. Navy stresses the strait is an international waterway crucial to global shipping and energy supplies.

Asked about why the Lincoln hadn't gone through the strait, Rear Adm. John F.G. Wade, the commander of the carrier's strike group, said that his forces could "conduct my mission wherever and whenever needed." He declined to discuss any specifics about that mission, though he said Iran had presented "credible threats" to the region.

"They do impose a threat to our operations, but also to the safety and security of commerce and trade going through the Strait of Hormuz and that's why we are here," Wade said.

The Lincoln hosted journalists from the AP and other media outlets on Monday. They spent some four hours aboard the vessel after a two-hour flight from the United Arab Emirates and were greeted by camera-carrying sailors who documented every part of their time onboard.

The Lincoln famously served as the backdrop of then-President George W. Bush's May 2003 speech declaring combat operations over in Iraq, a banner reading "MISSION ACCOMPLISHED" hanging behind him. The majority of the war's casualties came after.

On Monday, F/A-18s flew manoeuvrs over the carrier. Accompanying the Lincoln to the Mideast are three destroyers -- the USS Bainbridge, the USS Mason and the USS Nitze -- as well as the guided-missile cruiser the USS Leyte Gulf.

Capt. William Reed, the commander of the carrier's air wing, laughed off any notion the situation was stressful.

"It's just another day at the office," he said from the carrier's hangar as airmen worked on the ship's F/A-18 fighter jets.

Capt. Chris Follin, the commodore of the destroyer strike group travelling with the Lincoln, didn't express any concern, either.

"I wouldn't want to go against that," he said, nodding toward the ship's sailors and warplanes. "Our mission is just to keep the peace."

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Associated Press writer Fay Abuelgasim contributed to this report.