Iran shipped over 300,000 artillery shells and a million rounds of ammunition to Russia across the Caspian Sea in the past six months, according to a report by the Wall Street Journal.
Iran has mostly used cargo flights to ship weapons to Russia, which are nearly impossible for Western countries to stop, and blocking the shipment of weapons in the Caspian Sea would require the agreement of former Soviet republics in the area.
Officials in the Middle East told The Wall Street Journal that the most recent weapons shipment known to have crossed the Caspian Sea to Russia left Iran in early March on a Russian cargo ship, carrying 1,000 containers with 2,000 artillery shells.
Iran, Russia and the Caspian Sea connection
On April 24, US CENTCOM commander Michael "Erik" Kurilla visited Turkmenistan, which also borders the Caspian Sea. While Kurilla was in Turkmenistan, Turkmenistan Foreign Minister Rasit Meredow was in Washington, DC meeting with US Secretary of State Antony Blinken.
Last week, Israel opened its first-ever embassy in Turkmenistan.
This also comes after Vice-Adm. Brad Cooper of the US Fifth Fleet made an unannounced visit to Turkmenistan earlier this month, according to The Wall Street Journal.
The US Fifth Fleet is based out of Bahrain and is active in the Persian Gulf, Red Sea and Arabian Sea. Among their many responsibilities is maritime security in the region, which includes combatting attempted Iranian smuggling efforts.
For instance, on December 1, the US Navy managed to intercept an Iranian ship that was smuggling several weapons over to Yemen, where they would have gone to the Iran-backed Houthis.
US-allied British forces in the region have also intercepted several Iranian weapons smuggling attempts over the past few months.
This all comes amid deepening ties between Moscow and Tehran.
This stronger relationship was forged amid the Russian invasion of Ukraine, with Iran providing Russia with drones and Russia providing Iran with cash and seized Western weapons.
Exactly how Iran manages to ship these drones to Russia is unclear, though a report in The Guardian in February indicated that many of them were smuggled by way of Iranian ships on the Caspian Sea.