Iran and Russia have set up a new sea route for transporting military supplies through the Caspian Sea, according to a European government document cited by NBC News.
According to the document, which was confirmed by a Western official, Russia is shipping explosives, drone components, and munitions to Iran. These shipments are helping Tehran rebuild part of the military stockpile it lost during its war with the United States and Israel.
The cargo reportedly includes TNT, an explosive material that can be used, among other things, to build warheads.
The scale of the shipments and how far Iran’s arsenal has been rebuilt remain unknown, as Western intelligence agencies have not released public assessments on the matter.
The Caspian as a ‘Safe Corridor’ for Transport
The route Moscow and Tehran reportedly chose for moving the material matters a great deal. The Caspian is a landlocked sea bordered only by Russia, Iran, Kazakhstan, Turkmenistan, and Azerbaijan.
The legal status of the Caspian doesn’t allow armed forces from non-bordering countries to operate there. That means American or other Western warships can’t be deployed to intercept shipments moving between Russian and Iranian ports.
Ships can also switch off their Automatic Identification System (AIS) transponders, making it harder to track their movements.
This route lets the two countries bypass sea passages and chokepoints where the US and its allies have stronger surveillance capabilities.
Focus on Rebuilding Iran’s Drone Program
Particular weight is being placed on the drone components included in the shipments.
Before the war, Iran had built one of the region’s most significant drone programs, centered on its Shahed drones, which it had also supplied to Russia in large numbers for use in the war in Ukraine.
American and Israeli strikes hit a major share of Iran’s military capabilities. Restarting drone production requires both the necessary components and explosives for their warheads, materials that, according to the European document, are included in the Russian shipments.
A Reversal of Roles in Military Cooperation
This development is seen as significant because it partly reverses the roles Russia and Iran had held until recently in their military cooperation.
For years, the flow of military supplies moved mainly from Tehran to Moscow. Iran gave Russia drones and technical help in setting up production lines on Russian soil, supporting Moscow’s war effort in Ukraine.
Now, according to the new information, it’s Russia that is supplying Iran militarily.
For Moscow, strengthening Tehran also serves broader strategic goals. A militarily stronger Iran could force the US to keep more troops and resources in the Middle East, potentially limiting the attention and means it can devote to Ukraine.
Israeli Strikes on the Supply Line
This particular supply route had already been a target for Israel.
According to the Times of Israel, Israeli airstrikes in March 2026 hit the port of Bandar Anzali on Iran’s northern Caspian coast.
The strikes destroyed port infrastructure and vessels belonging to Iran’s navy, with Israeli officials saying the goal was to disrupt this specific supply line.
However, the European document cited by NBC News suggests the shipments either continued or resumed after the Israeli strikes.
The strike on Bandar Anzali therefore appears to have caused a temporary pause or a change of route rather than a permanent shutdown of the line.
Difficulties in Stopping the Flow
The Caspian’s geography complicates any effort to intercept the shipments. The five coastal countries have a range of ports, which allows routes to be varied and makes it hard to shut down the network by striking a single facility.
For their part, Moscow and Tehran have not publicly commented on these shipments. It also remains unclear whether the volume of Russian material is enough to offset the losses Iran’s arsenal has suffered from American and Israeli strikes since the war began.
