US preparing weeks-long military operation against Iran, sources say

Citing anonymous US officials, Reuters reports that the US military is preparing for a weeks-long operation against Iran if Trump orders it. The US is currently engaged in direct talks with Iran for the first time in years on the subject of Iran’s nuclear program. The Trump administration, at the urging of Israeli Prime Minister Benjamin Netanyahu, is also seeking to disarm Iran’s highly-capable arsenal of ballistic missiles. The Iranians have shown willingness to discuss limits on their nuclear program and have sweetened their offer with potential trade and energy deals with the US. However, Iran has insisted that curbs on its missile program remain off the table.

In a show of force, the US has in recent weeks dispatched two aircraft carriers to the region. The USS Abraham Lincoln has already arrived and the USS Gerald R. Ford is en route from the Caribbean. In addition, the Pentagon has surged troops to its bases in the region, with the total number up to around 50,000, up from around 34,000 a couple of years ago.

While President Trump has repeatedly shown reluctance to involve the US in protracted military conflicts, he has recently called for regime change in Iran. However, it is unclear if regime change would be the goal of any potential military operation.

What are the prospects of success in a regime-change war?

Over 7 weeks from March to May 2025, the US carried out an intensive bombing campaign against the Houthis in Yemen, one of Iran’s regional allies. Despite bombing thousands of targets and killing dozens of high-ranking Houthi civilian and military officials, the US failed to dismantle the Houthi command structure or even significantly diminish their military capacity. Ultimately, the US was forced to sign a truce with the Houthis, which did not even demand the Houthis cease launching missiles at Israel in support of the Palestinians.

While the Houthis are highly organized, they are nowhere near as well-equipped as their chief suppliers in the Iranian military. If Trump’s goal in striking Iran is to end the Ayatollah’s regime, a bombing campaign from miles out to sea is unlikely to succeed. A full-scale invasion would be required, a campaign which would dwarf the 2003 invasion of Iraq. Despite Iran’s mountainous and inhospitable terrain, there are historical precedents for successful military conquests of Iran from outsiders.

The last time Iran was successfully militarily invaded, conquered, and occupied was in the 1941 Anglo-Soviet invasion during World War II. In this case, a combined invasion force of about 60,000 troops overwhelmed Iran’s defenses in about two weeks. However, 1941 Iran is not 2026 Iran. Today’s Iranian military is far more organized and well-equipped than was the case in 1941. Thanks to its decentralized nature, Iran’s command-and-control structure also proved itself to be resilient to decapitation strikes by the Israelis in July 2025.

The US officials who spoke to Reuters said they fully expect Iran to retaliate forcefully, both against US military bases in the region and against nearby US ships. This could lead to immense losses of both US military personnel and equipment.

What happens if they are successful?

Even in the event a large-scale US military operation were successful in toppling the Ayatollah, what would follow is highly uncertain.

US officials seem to believe that ongoing civil unrest in Iran will work in their favor. However, when it comes to attacks from the outside, a country’s citizens tend to rally around their existing government, even if they otherwise despise it. The US government and media has touted Reza Pahlavi, son of the long-deposed Shah (or king) of Iran, as a potential figurehead to lead a post-Ayatollah government. Much has been made much of some Iranian protesters adopting Pahlavi as a potential unifying figure. However, their enthusiasm for the Shah is likely to be dampened if he takes power following a military campaign that kills thousands of Iranians (one he has personally and repeatedly cheered for).

Another possibility is that Iran will fall into years of civil war, similar to what happened after the US toppled Saddam Hussein in Iraq and Muhammar Gaddafi in Libya. Apart from this being disastrous for the Iranian people, it would also mean that other militant forces in the region would be unleashed.

Iran’s Revolutionary Guard Corps (IRGC) has supplied and trained dozens of militias in Iraq, Syria and elsewhere. When it wishes, Iran is able to restrain these forces from attacks on US military bases for example. These groups are ideologically committed to eliminating Western influence in the region. If the IRGC is decapitated, it is unlikely that these militants would quietly disappear. This would likely result in deadly retaliation attacks, both against US forces in the region and against their allies in Israel and elsewhere.