How long will the Iran war last? Experts weigh in on the debate

Since the US and Israel launched a surprise attack on Iran last weekend, Washington has been keen to stress that the military action will end within weeks and will not become a so-called “permanent war”.

But if the Iranian regime proves more resilient than expected, the U.S. could easily be embroiled in “Operation Epic Fury” and the conflict drags on, experts say.

“What we’re seeing is more complicated than the White House expected,” Suzanne Maloney, vice president and director of foreign policy at the Brookings Institution, told CNBC on Tuesday.

“Obviously, the start of the conflict with the quick announcement that Iran’s Supreme Leader Ayatollah Ali Khamenei had been killed was a huge success in many respects, and the US and Israel were able to inflict immense damage on Iran’s military capabilities.”

“But the day after is enormously complicated, and I’m not optimistic that we’re going to see a quick end to this conflict, because the Iranians are escalating across the region, and that’s their long-term game plan,” he said.

When airstrikes began targeting Iran’s leadership and military sites last Saturday, killing Khamenei in his compound within hours, it quickly became clear that the attacks would not be “one and done.”

But US President Donald Trump said last week that the military operation in Iran would end in “four to five weeks” and top officials from Vice President JD Vance to Defense Secretary Peter Hegseth stressed that it would not be a protracted, low-burn conflict of the kind seen in Afghanistan or Iraq.

Such so-called “perpetual wars” have proven controversial and unpopular with the American public, and are especially resented by Trump’s MAGA fans, who want the president to prioritize domestic over foreign policy. Only one in four Americans support an attack on Iran, a Reuters/IPSOS poll found last week, and there have been protests in Washington against the strikes.

The US and Israel initially said their primary goal was to wipe out Iran’s nuclear program once and for all, but that war’s goals appear to have shifted this week, from destroying Iran’s ballistic missile program to wanting to protect the American public from an imminent, but unspecified, Iranian threat.

According to William Roebuck, former US ambassador to Bahrain and current executive vice president of the Arab Gulf States Institute, Trump is very wary of public opinion when it comes to operations in Iran.

“It’s a dangerous proposition for them. There’s a possibility of disruption in the economy, which they’re very focused on. It could cause jolts in the energy markets. It could also cause jolts in the stock market, which they’re very focused on,” Roebuck told CNBC on Wednesday.

“They haven’t really made the case in the United States for going to Iran and taking this military action. They’ve shifted a little bit in the rationales (terms) they’ve given, and polling suggests that only one in four Americans get that rationale and support it,” Roebuck noted.

“For those reasons it’s a bit dangerous for their base,” he said.

The big unknown is whether the US will seek regime change in the Islamic Republic after Khamenei’s death, and if so, who or what should replace the supreme leader.

Hegseth stressed on Monday that the military operation was not about regime change: “It’s not called a regime change war, but the regime has certainly changed,” referring to Khamenei’s death, along with other senior officials.

Torbjörn Soltvedt, principal Middle East analyst at Verisk Maplecroft, said US officials were looking for “a very quick solution to this conflict” but as things stand now, “we have to brace for a potentially extended conflict”.

“We’ve heard President Trump talk about a four- to five-week operation, but Iran is a huge country with a huge population, a very extensive security apparatus, so it’s going to be very difficult to try to disengage and move toward some kind of interim solution. But those kinds of conversations are probably premature at this point,” he said.

Analysts agree that the US’s game plan – or rather, its end game – is unclear and determining how long a military operation will take is tricky. Many compare the current operation in Iran to a “gamble” on Trump’s part.

If the goal is regime change, experts say, American boots on the ground are likely to be needed in Iran — something Washington may well hold back, given public opinion and the potential ramifications for a Republican administration.

“American forces cannot be used to invade a country the size of Iran. It’s not some small country, it’s a vast country,” Malcolm Rifkind, the UK’s former foreign and defense secretary, warned CNBC, adding, “It could be Iraq again and it’s not going to happen.”

Reluctant to get embroiled in a potentially lengthy and bloody ground war, analysts say a short and targeted military operation is possible — but it ultimately depends on what Trump wants and how long Iran’s leadership can survive a US-Israeli attack.

Robert Macair, the former UK ambassador to Iran, admitted that “perpetual war” was not a possible scenario because Iran did not have the capacity to continue retaliating “indefinitely”.

“Launchers are being followed by strikes, the Iranian command says, there must come a point where launches become infrequent and this may stop,” he said.

Signum Global Advisors’ Charles Myers says there is only one outcome to the conflict: Iran loses.

“This is not a long-term or medium-term war … There is only one outcome here, and that is Iran losing. Iran is fighting two of the most powerful, sophisticated militaries in the world, and Iran is going to lose this war. The question is what defeat will look like and how long it will take,” he told CNBC Thursday.

Myers expects the kinetics part of the battle to be “done in the next three to four days.”

“And after that, you’ll start to hear the US president talking about an off ramp or a victory or a victory. And from there I think we’ll see a movement toward trying to come to some kind of settlement or agreement … it’s not going to be a protracted military operation,” he said.