Ukraine said it is considering cutting relations with Iran if Russia uses ballistic missiles supplied by Tehran to target Ukraine while condemning any such delivery.
Earlier, U.S. Secretary of State Antony Blinken said Russia received the missiles from Iran 2-1/2 years after the full-scale invasion. He said he expected Moscow to use the weapons in the coming weeks. Iran has denied supplying the arms.
Ukraine, which has already been grappling with an increase in Russian missile and drone attacks, has said there would be devastating consequences for its bilateral ties with Iran if reports of the missile supplies are confirmed.
"I will not say now exactly what is meant by devastating consequences, so as not to weaken our diplomatic position. But I can say that all options, including the one you mentioned, are on the table," foreign ministry spokesman Heorhiy Tykhyi said when asked if Kyiv could cut ties with Tehran.
President Volodymyr Zelenskiy made no direct reference to Iran in his nightly video address but pledged to coordinate a strong worldwide response to any power helping Russia and President Vladimir Putin.
"I want to say to everyone in the world who still wants somehow to help Putin," Zelenskiy said.
"We will do everything not just to defend our state and people, but to truly consolidate the world for strong responses to the incitement of war or any attempts to prolong it."
Ukraine's allies, including the U.S., have said the delivery amounts to a substantial escalation and that they will impose further sanctions on Iran.
While describing such sanctions as a "positive step", Ukraine's top presidential official, Andriy Yermak, said it would not be enough on its own.
"We also need authorization to use Western weapons against military targets on Russian territory, the provision of longer-range missiles, and the enhancement of our air defense systems," Yermak said on X.
The Kremlin has yet to comment on Blinken's statements. On Monday, it said it was developing all-round dialogue with Iran.
Ukraine downgraded ties with Iran in 2022 over Tehran's supply of unmanned Shahed attack drones to Russia, which Moscow troops have since used for regular long-range attacks.
Until now, Iranian military support for Moscow has been most visible in the supply of those drones, which carry a smaller payload and are easier to shoot down because they travel at a fraction of the speed of ballistic missiles.
Reuters reported in August that Russia expected delivery of hundreds of Fath-360 close-range ballistic missiles from Iran and that dozens of troops had received training to fire them.