Several senior Russian missile specialists have visited Iran over the past year as the Islamic Republic has deepened its defence cooperation with Moscow, a Reuters review of travel records and employment data indicates.

The seven weapons experts were booked to travel from Moscow to Tehran aboard two flights on April 24 and September 17 last year, according to documents detailing the two group bookings as well as the passenger manifest for the second flight.

The booking records include the men's passport numbers, with six of the seven having the prefix "20". That denotes a passport used for official state business, issued to government officials on foreign work trips and military personnel stationed abroad, according to an edict published by the Russian government and a document on the Russian foreign ministry's website.

Reuters was unable to determine what the seven were doing in Iran.

A senior Iranian defence ministry official said Russian missile experts had made multiple visits to Iranian missile production sites last year, including two underground facilities, with some of the visits taking place in September. The official, who requested anonymity to discuss security matters, didn't identify the sites.

A Western defence official, who monitors Iran's defence cooperation with Russia and also requested anonymity, said an unspecified number of Russian missile experts visited an Iranian missile base, about 15 km (9 miles) west of the port of Amirabad on Iran's Caspian Sea coast, in September.

Reuters couldn't establish if the visitors referred to by the officials included the Russians on the two flights.

The seven Russians identified by Reuters all have senior military backgrounds, with two ranked colonel and two lieutenant-colonel, according to a review of Russian databases containing information about citizens' jobs or places of work, including tax, phone and vehicle records.

Two are experts in air-defence missile systems, three specialize in artillery and rocketry, while one has a background in advanced weapons development and another has worked at a missile-testing range, the records showed. Reuters was unable to establish whether all are still working in those roles as the employment data ranged from 2021 to 2024.

Their flights to Tehran came at a precarious time for Iran, which found itself drawn into a tit-for-tat battle with arch-foe Israel that saw both sides mount military strikes on each other in April and October.

Reuters contacted all the men by phone: five of them denied they had been to Iran, denied they worked for the military or both, while one declined to comment and one hung up.

Iran's defence and foreign ministries declined to comment for this article, as did the public relations office of the Islamic Revolutionary Guard Corps, an elite force that oversees Iran's ballistic missile program. The Russian defence ministry didn't respond to a request for comment.

Cooperation between the two countries, whose leaders signed a 20-year military pact in Moscow in January, has already influenced Russia's war on Ukraine, with large numbers of Iranian-designed Shahed drones deployed on the battlefield.

ROCKETS AND ARTILLERY

The flight booking information for the seven travellers was shown to Reuters by Hooshyaran-e Vatan, a group of activist hackers opposed to the Iranian government. The hackers said the seven were travelling with VIP status.

Reuters corroborated the information with the Russian passenger manifest for the September flight, which was provided by a source with access to Russian state databases. The news agency was unable to access a manifest for the earlier flight, so couldn't verify that the five Russian specialists booked on it actually made the trip.

Denis Kalko, 48, and 46-year-old Vadim Malov were among the five Russian weapons experts whose seats were booked as a group on the April flight, the records showed.

Kalko worked at the defence ministry's Academy for Military Anti-Aircraft Defence, tax records for 2021 show. Malov worked for a military unit that trains anti-aircraft missile forces, according to car ownership records for 2024.

Andrei Gusev, 45, Alexander Antonov, 43, and Marat Khusainov, 54, were also booked on the April flight. Gusev is a lieutenant-colonel who works as deputy head of the faculty of General Purpose Rockets and Artillery Munitions at the defence ministry's Penza Artillery Engineering Institute, according to a 2021 news item on the institute's website. Antonov has worked at the Main Rocket and Artillery Directorate of the Defence Ministry, according to car registration records from 2024, while bank data shows Khusainov, a colonel, has worked at the Kapustin Yar missile-testing range.

One of the two passengers onboard the second flight to Tehran in September was Sergei Yurchenko, 46, who has also worked at the Rocket and Artillery Directorate, according to undated mobile phone records. His passport number had the prefix "22"; Reuters was unable to determine what that signified though, according to the government edict on passports, it isn't used for private citizens or diplomats.

The other passenger on the September flight was 46-year-old Oleg Fedosov. Residence records give his address as the office of the Directorate of Advanced Inter-Service Research and Special Projects. That is a branch of the defence ministry tasked with developing weapons systems of the future.

Fedosov had previously flown from Tehran to Moscow in October 2023, according to Russian border crossing records viewed by Reuters. On that occasion, as he did for the September 2024 flight, Fedosov used his passport reserved for official state business, the records showed.