A new supply route for military equipment from Russia to Iran via the Caspian Sea has been revealed by a European government document cited by NBC News.

According to the document, whose contents were confirmed by a Western official, Russia is transferring explosives, components for unmanned aerial vehicles and ammunition to Iran, helping Tehran replenish some of the military equipment it lost during the war with the US and Israel.

The shipments include trinitrotoluene (TNT), an explosive that can be used, among other things, in the manufacture of warheads.

The scale of the transfers and the extent to which Iran’s military arsenal has been rebuilt remain unknown, as Western intelligence agencies have not released relevant assessments.

Why the Caspian is a “secure corridor”

Particular significance is attached to the route Moscow and Tehran are reportedly using to transport the material. The Caspian is an enclosed sea whose shores are exclusively occupied by Russia, Iran, Kazakhstan, Turkmenistan and Azerbaijan.

The legal status of the Caspian does not permit the presence of armed forces from countries that do not border it. In practice, this means that US or other Western warships cannot be deployed there to intercept cargo moving between Russian and Iranian ports.

At the same time, vessels can switch off the transponders of the Automatic Identification System (AIS), making it more difficult to monitor their movements.

The route therefore allows the two countries to bypass maritime passages and locations where the US and its allies have significantly greater surveillance capabilities.

Aim is to rebuild Iran’s drone program

Particular importance is being attached to the drone components included in the shipments.

Before the war, Iran had developed one of the region’s most significant unmanned aircraft programmes, centred on the Shahed drones, which it had supplied in large numbers to Russia for use in the war in Ukraine.

US and Israeli attacks struck a significant part of Iran’s military capabilities. Restoring drone production requires both the necessary components and explosives for their warheads – materials which, according to the European document, are included in the Russian shipments.

Reversal of roles between Moscow and Tehran

The development is considered significant for another reason as well: to some extent, it reverses the roles Russia and Iran had until recently played in their military cooperation.

For years, the flow of military equipment had mainly moved from Tehran to Moscow. Iran supplied Russia with drones, as well as technical assistance to develop related production lines on Russian soil, strengthening Moscow on the Ukrainian front.

Now, according to the new information, Russia is the one supplying Iran with military equipment.

For Moscow, strengthening Tehran also serves broader strategic objectives. A militarily stronger Tehran could force the US to maintain more forces and resources in the Middle East, potentially limiting the attention and resources it can devote to Ukraine.

Israel struck the route in March

The supply route had already come under Israeli attack.

According to the Times of Israel, Israeli air strikes in March 2026 hit the port of Bandar Anzali, on Iran’s northern Caspian coast.

The attacks destroyed port infrastructure and Iranian naval vessels, with Israeli officials saying the aim was to disrupt the specific supply route.

However, the details in the European document now cited by NBC News indicate that the shipments either continued or resumed following the Israeli strikes.

The attack on Bandar Anzali therefore appears to have caused more of a temporary interruption or diversion than the permanent closure of the route.

Difficult to halt the flow

The geography of the Caspian makes any attempt to intercept the shipments even more complicated. The five coastal countries have a number of ports, allowing routes to be diversified and making it more difficult to neutralise the network by striking a single facility.

Moscow and Tehran have not publicly commented on the specific shipments. It also remains unclear whether the quantity of Russian material is sufficient to offset the losses suffered by Iran’s arsenal as a result of US and Israeli strikes.