While Iran has so far avoided confirming or denying U.S. assertions that Russian missiles aimed at antigovernment forces in Syria instead landed in that country, local reports have emerged of explosions and flying objects in several Iranian towns.
The question of missile reliability in the early days could prove damaging to Russia's military campaign in Syria, which already has raised hackles in Turkey and the West.
U.S. Defense Secretary Ash Carter on October 9 cited indications that four Russian cruise missiles crashed as they flew over Iranian territory this week, suggesting there were malfunctions.
Russian warships in the Caspian Sea reportedly launched 26 cruise missiles in an aerial assault on targets in Syria on October 7, implying a flight path over Iranian territory.
Local news reports -- many of which have since been taken down -- have mentioned sightings of unidentified flying objects, and eyewitnesses have reported seeing explosions and damaged buildings. The reports have emerged from the northwestern provinces of West Azerbaijan and Kurdistan, and in Gilan Province, which borders the Caspian Sea.
Merian News, a news outlet in Gilan, reported on October 7 that locals witnessed a "luminous object in the sky." They described an object like a "drone that was flying at low altitude."
News outlet Golan Saqaz reported at least one unidentified object over Kurdistan Province.
In the Iranian town of Astara, near the border with Azerbaijan, locals in the early hours of October 7 reported hearing a "crashing sound," according to the Iranian news website Entekhab.ir.
Meanwhile, residents of Takab, a city in West Azerbaijan Province, claimed an "unidentified flying object" had crashed near the village of Qizqapan. Evian News reported that the force of the blast damaged homes and shattered windows.
Takht News, meanwhile, reported on October 8 that the blast in Qizqapan had injured two people and had killed livestock.
It added that "security forces were in the area" and were examining debris from the flying object.
Takab's governor told IRNA news agency that the cause of the crash was "unclear."
Footage posted by an Iraqi Kurdish Peshmerga account has also emerged purporting to show two "Russian missiles" flying at low altitude over Iraq on October 7.
Iranian Foreign Ministry spokeswoman Afkham Marzieh said on October 9 that "we don't confirm" this information when asked about the U.S. claim that four Russian cruise missiles had landed in Iran.
Iranian Brigadier General Moussa Kamali told Russian state news agency Sputnik on October 9 that the U.S. claims were a "blatant lie" and an attempt at psychological warfare.
"We haven't been told of any falling Russian missiles in Iran. All of these reports that Russian missiles launched at Syria and allegedly fell in Iran are blatant lies," Kamali said.
Russia's Defense Ministry has flatly denied the claim.
"Any professional knows that during these operations we always fix the target before and after impact. All our cruise missiles hit their target," ministry spokesman General Igor Konashenkov said on October 9.
Russia posted a graphic on the Defense Ministry website on October 7 depicting 26 missiles flying over Iran and Iraq before striking inside Syria, where it has been conducting air strikes in defense of President Bashar al-Assad since September 30.
Russia and Iran, both allies of the embattled Assad, recently signed a new security and intelligence-sharing agreement and have a joint control center in Baghdad.
RFE/RL's Radio Farda contributed to this report