An Iranian general has claimed that the country had developed a hypersonic missile capable of penetrating all defence systems, raising concerns from the UN nuclear watchdog.
Hypersonic missiles, which like traditional ballistic missiles can deliver nuclear weapons, can fly at more than five times the speed of sound.
"This hypersonic ballistic missile was developed to counter air defence shields," General Amirali Hajizadeh, the commander of the Islamic Revolutionary Guard Corps aerospace unit, was quoted as saying by Fars news agency.
"It will be able to breach all the systems of anti-missile defence," he said, adding that he believed it would take decades before a system capable of intercepting it is developed.
The head of the International Atomic Energy Agency (IAEA) Rafael Grossi, speaking at a UN climate summit in Egypt, expressed concerns about the announcement.
"We see that all these announcements increase the attention, increase the concerns, increase the public attention to the Iranian nuclear programme," Mr Grossi told AFP.
But he added that he does not see this as "having any influence" on negotiations over the Islamic republic's nuclear programme.
The announcement comes after Iran admitted on Saturday that it had sent drones to Russia, but said it had done so before the Ukraine war.
The Washington Post reported on 16 October that Iran was preparing to ship missiles to Russia, a report Tehran rejected as "completely false".
It also comes at a time protests have rocked Iran since the 16 September death of Mahsa Amini after her arrest for allegedly flouting the country's hijab dress code for women.
Stalled nuclear talks
Unlike ballistic missiles, hypersonic missiles fly on a trajectory low in the atmosphere, able to reach targets more quickly.
North Korea's test of a hypersonic missile last year sparked concerns about the race to acquire the technology, which is currently led by Russia, followed by China and the United States.
Both Iran and Russia are targeted by stringent sanctions - Iran after the US unilaterally pulled out of the 2015 nuclear deal, and Russia since it invaded Ukraine in February.
The two countries have responded to the sanctions by boosting cooperation in key areas to help prop up their economies.
Iran yesterday hosted Russia's security chief Nikolai Patrushev for talks on subjects that the Russian side said included "the fight against terrorism and extremism" as well as measures to counter Western interference.
A hypersonic missile is manoeuvrable, making it harder to track and defend against.
While countries including the US have developed systems designed to defend against cruise and ballistic missiles, the ability to track and take down a hypersonic missile remains a question.
Today's announcement comes against a backdrop of stalled talks on reviving the 2015 nuclear deal.
The deal Iran reached with Britain, China, France, Germany, Russia and the US gave it relief from sanctions in return for guarantees it could not develop an atomic weapon.
Iran has always denied wanting a nuclear arsenal.
The deal collapsed after the US's unilateral withdrawal in 2018 under then president Donald Trump.
The IAEA said it had seen "no progress" in discussions with Iran over undeclared nuclear material at three sites, a sticking point in the talks aimed at reviving the accord.
Iran has been enriching uranium well over the limits laid down in the 2015 deal with world powers, which started to unravel when the United States withdrew from it in 2018.
Warning to Saudi Arabia
Iran's claim to have developed a hypersonic missile follows its announcement on 5 November of the successful test flight of a rocket capable of propelling satellites into space.
The US has repeatedly voiced concern that such launches could boost Iran's ballistic missile technology, extending to the potential delivery of nuclear warheads.
In March, the US government imposed sanctions on Iran's missile-related activities.
Iran on Wednesday warned its neighbours including Saudi Arabia that it would retaliate against moves to destabilise it amid the protests sparked by Amini's death.
"I would like to say to Saudi Arabia that our destiny and that of other countries in the region are linked to each other," Intelligence Minister Esmail Khatib said.
"Iran has so far adopted strategic patience but it cannot guarantee that it will maintain this strategic patience if hostilities against it continue.
"If the Islamic republic decides to punish these countries, their glass palaces will collapse and they will no longer enjoy stability," said Mr Khatib.