ManyVoices

Bright orange flashes and a roiling funnel of black smoke filled the air as Israeli fighter jets struck Iran’s naval command center at the port of Bandar Anzali. Israel said it also destroyed several Iranian navy vessels and called the strike “one of the most significant” it had conducted during combat operations against Iran.

Yet the attack in March, captured in footage released by Israel’s military, happened not on the strategically critical Persian Gulf, but on the Caspian Sea, a huge body of water hundreds of miles north. Routinely overlooked, the Caspian has taken on new significance as a trade route linking Russia and Iran.

For two allies that have been embroiled in wars and facing more Western sanctions than any other country, the waterway provides a passageway for both overt and covert trade — shipments that have helped Iran persist as an adversary to the United States despite overwhelming American military superiority.

Russia is shipping drone components to Iran via the Caspian Sea, U.S. officials say, helping Iran rebuild its offensive abilities after losing roughly 60 percent of its drone arsenal during recent fighting. The officials spoke anonymously to divulge private military assessments.

Russia also provides goods that would typically pass through the Strait of Hormuz, now blockaded by the U.S. Navy, as part of global trade.