Despite US-Israeli airstrikes that have killed its top leaders and inflicted huge material damage, Iran's governing system remains in place and it retains the ability to fire missiles and drones at its neighbours and Israel.

Above all, it has demonstrated its ability to choke off the Strait of Hormuz shipping route, spiking oil and gas prices and underlining how it has a sizeable part of the world economy at its mercy.

Trump sprung a surprise on Monday by announcing talks with Tehran, but Iranian officials have insisted all week that no negotiations are taking place, even mocking the US leader for "negotiating with himself".

Foreign Minister Abbas Araghchi told state TV late on Wednesday that "speaking of negotiations now is an admission of defeat", but a response has been sent to Washington's 15-point plan via an intermediary, Iranian media reported.

Trump warned Thursday that Iran "better get serious soon" about the talks or face unspecified consequences -- a tacit admission that Tehran was not rushing for a settlement as he has previously claimed.

- Deterrence -

Ross Harrison, a senior fellow at the Middle East Institute think tank and author of "Decoding Iran's Foreign Policy", said he detected that Iranian leaders "are getting quite confident in themselves right now in some ways".

Given their utter distrust of Trump, who has bombed Iran twice amid negotiations in the last year, Tehran is naturally sceptical about talks and looking to create deterrence against another attack, he said.

That would come in the form of inflicting "enough pain" on the United States, and the global economy more broadly, that Trump or Israel would think twice about bombing Iran again in the future.

Iran's strategy "is much simpler than it is for the Americans: it's regime survival and recreating deterrence so that this is not going to happen again six months from now, a year from now, two years from now", Harrison told AFP.

But he noted that there's "a lot of bravado going on on all the sides", and cautioned that the Iranians "should worry about overplaying their hand".

Another factor driving Iran's response is the promotion of hardliners in Tehran power circles during the war, including the new supreme leader Mojtaba Khamenei and new security chief Mohammad Bagher Zolghadr.

The appointment of Zolghadr, a hawkish veteran of the 1980s Iran-Iraq war, signalled "a much more aggressive Iranian posture", wrote Vali Nasr, a prominent Iranian-American author and academic.

- Struggle -

Guillaume Lasconjarias, a Middle East expert at the Sorbonne University in Paris, noted how Trump had gone from demanding "unconditional surrender" to proposing a 15-point peace plan.

"In negotiations, the one who extends their hand first appears to be in the weaker position," Lasconjarias told AFP, referring to Trump.

"Appearances are probably deceiving, however, because Iran has been very much weakened," he added.

A large part of its political and military elite has been assassinated, while its missile sites, nuclear programme, domestic security forces and navy have been relentlessly targeted with airstrikes.

Its economy, already suffering from sky-high inflation and sanctions before the war, is at a near-standstill.

The outcome may boil down to how badly Trump wants a quick exit from the war, and how long Iran estimates it can hold out, even in the event of further escalation from the US.

The US leader set a five-day deadline that will expire on Saturday, threatening to "unleash hell" unless Iran met his demands on its nuclear and missile programmes, as well as reopening the Strait of Hormuz.

Robert Pape, a political science and military expert at the University of Chicago, believes the talks are a smokescreen as Trump moves thousands of airborne troops and marines to the Gulf for a possible ground offensive.

"If you want to understand where this war is going, ignore what is said. Watch what moves," he wrote on his Substack.

An Iranian military official, quoted by state media, signalled Wednesday that Tehran would retaliate to a ground invasion by activating its Houthi rebels in Yemen to attack shipping in the Red Sea, dramatically widening the conflict.