The US has deployed the most air power in the Middle East since the 2003 invasion of Iraq.

Yet it has still not been determined whether President Trump would order a strike against Iran – and if he did, whether it would be aimed at halting Iran’s already troubled nuclear program, eliminating its missile power. try to topple the regime.

Over the past few days, the US has continued to send state-of-the-art F-35 and F-22 jet fighters to the Middle East, according to flight-tracking data and a US official. A second aircraft carrier Coming loaded with attack and electronic-warfare aircraft. Command-and-control aircraft, critical to organizing large air operations, are on the way. And significant air defenses have been deployed in the region in recent weeks.

This lethality would give the US the option of carrying out a sustained, weeks-long air war against Iran rather than the one-off “Midnight Hammer” strike it carried out against Iran in June. Iranian nuclear siteUS officials said.

Representatives of the US and Iran met in Geneva this week to negotiate a possible deal on uranium enrichment in Iran. White House press secretary Carolyn Leavitt said “a little progress” has been made in those talks, but added, “We’re still a long way apart on some issues.” Iran is expected to present a more detailed proposal to the United States in the next few weeks, Levitt said.

US officials said Trump has received multiple briefings on his military options if he chooses to attack, all of them designed to inflict maximum damage on Iran’s regime and its regional proxies.

U.S. and foreign officials said options included a campaign to kill several Iranian political and military leaders with the goal of overthrowing the government, as well as an air strike that would be limited to striking targets including nuclear and ballistic-missile facilities. Both will involve potentially week-long operations.

US officials said Trump had not yet decided whether to order strikes against Iran. His national-security advisers discussed Iran during a meeting in the White House Situation Room on Wednesday, according to a senior administration official.

Trump has indicated he would prefer a diplomatic agreement in which, if the US gets everything it wants, Iran’s nuclear programs would be dismantled, regional proxy forces would be disbanded and ballistic missiles would be destroyed. It is believed that Iran is unlikely to agree to the last point, as it does not have much of an air force and relies on missiles as its main deterrent. Trump has indicated that he cares primarily about the nuclear issue, telling reporters that he would like Iran to stop uranium enrichment.

Meanwhile, some advisers and foreign leaders, such as Israeli Prime Minister Benjamin Netanyahu, are telling Trump he should use US military pressure to extract more concessions from Tehran. According to officials, Israel particularly wants to see Iran’s ballistic-missile production ended.

Not all of the weapons the US could use to attack Iran are currently in the Middle East, nor are they needed. B-2 stealth bombers have long been trained to carry out Middle East missions directly from the US, as they did against Iran’s nuclear facilities in June, or from the joint US-UK base at Diego Garcia in the Indian Ocean. Other long-range American bombers can do the same.

Trump wrote in a social-media post on Wednesday that it might be necessary for the US to use Diego Garcia, a UK-controlled island in the Indian Ocean, to launch a strike if Iran does not keep the nuclear deal. Trump also said the US could use Fairford Airport in Britain during the operation.

The US military, with its stealth technology and standoff-precision weapons, holds a massive edge over Iran, whose air defenses were battered by Israel last year.

Iran has some cards to play in a sustained campaign, including a still-large missile arsenal that could be directed at U.S. bases and allies in the region, and military forces that could try to close the Strait of Hormuz, a vital sea route for oil tankers.

Given the uncertainties, some former military officers said a diplomatic settlement might be better than war.

“Frankly, the best thing that could come from this is that a dramatic increase in deployed forces would be quite significant as an indicator that Trump is not messing around with the use of force,” said David Deptula, a retired three-star Air Force general who played a key role in the 1991 Desert Storm campaign against Iraq. Thus Iran’s leaders were induced to come to an agreement.

But US and foreign officials are becoming increasingly pessimistic that Iran will agree to US demands. Instead, he said, Tehran might be willing to suspend its nuclear-enrichment activities only for a short period of time — perhaps until Trump is out of office.

According to foreign officials familiar with Tehran’s thinking, Iran hopes it can use negotiations to delay any US attack, but it also realizes that Trump could become frustrated by lengthy negotiations and order an attack.

Trump has repeatedly threatened to attack Iran if talks fail. “I don’t think they want the outcome of no deal,” he told reporters on Monday.

The U.S. Air Force recently moved dozens of jet fighters and support aircraft to Jordan’s Muwafaq Salti Air Base and Saudi Arabia’s Prince Sultan Air Base, according to flight-tracking data. These include additional F-35s, F-15s, F-16s, E-3 Airborne Warning and Control System and E-11 Battlefield Airborne Communications Node aircraft. More fighter planes are coming.

Meanwhile, the US Navy currently has 13 ships in the Middle East and eastern Mediterranean to support a potential campaign, including the aircraft carrier USS Abraham Lincoln and nine destroyers capable of defending against ballistic missiles, according to a Navy official. A second aircraft carrier, USS Gerald R. Ford, and four destroyers of its strike group are on their way.

The Wall Street Journal previously reported that the Pentagon has deployed additional land-based air defenses across the Middle East.

As formidable as the buildup appears, it is a mere fraction of the assets the US deployed in the 1991 Gulf War or the 2003 invasion of Iraq. To the east, the US deployed six aircraft carriers to the Persian Gulf and the Red Sea. Prior to that operation, the U.S. Air Force had deployed entire wings of warplanes, rather than the squadrons being sent now, to carry out a six-week air campaign.

US Air Force deployed for Operation Iraqi Freedom in 2003 863 aircraft in the Middle East. Including Operation Desert Storm in 1991 1,300 American aircraft From the Air Force, Navy and Marine Corps, according to information from Air & Space Forces Magazine.

Today’s circumstances are different. The US air force is now much smaller, and there are no US and allied ground forces to support. Nor is there any international coalition, unless the Israeli Air Force joins the operation.

Unlike in 1991, Saudi Arabia and the United Arab Emirates have closed their airspace to potential US attacks. Many US warplanes are concentrated in Jordan.

But military technology, including the ability to conduct precision strikes, use covert technology, and use space, has improved.

The Trump administration is still unsure what might happen after the bombing campaign. Secretary of State Marco Rubio told lawmakers in January that the US had no clarity on who would take power if Supreme Leader Ali Khamenei fell. Many analysts believe Islamic Revolutionary Guard Corps leaders will likely take control.

Anti-regime Iranians, whom Trump pledged support for during protests that government officials violently suppressed in January, may revive demonstrations following the US bombing campaign, sensing an opportune moment to increase public pressure on their rulers. However, it could also leave the US with a dilemma about whether to prolong the air war if the regime were to take action again.

Eliot Cohen, who led the study of the use of air power in Desert Storm for the Air Force and is now a scholar at the Center for Strategic and International Studies, said a punitive air campaign could seek to weaken Iran’s leadership in such a way that surviving members of the elite would agree to a far-reaching deal with Washington.

“If Trump really wants to influence the regime and reduce its ability to use missiles to attack U.S. bases, Israel, Saudi Arabia and the Gulf states, it will likely take an intense campaign that will last for weeks and possibly months,” he said.

Write to Lara Seligman lara.seligman@wsj.comMichael R. gordon at michael.gordon@wsj.comin alexander ward alex.ward@wsj.com and shelby on holiday shelby.holliday@wsj.com