More strain on the international shipping network emerged after Ukraine struck an Iranian cargo ship in the Caspian Sea on July 25. The New York Times reports that the attack has underscored the links between the wars that the two countries are fighting, raising the risk of more direct confrontation.

With the Strait of Hormuz effectively closed, and the Houthis threatening international shipping in the Red Sea, shippers must add the Black Sea and the Caspian Sea to areas that are unsafe.

Ukraine said the ship was carrying military equipment between Iran and Russia. Iranian officials said it was a commercial vessel, and it accused Ukraine of killing a sailor in the attack.

Iranian officials threatened retaliation in a series of statements and comments to the news media. In a post on X, Abbas Araghchi, the Iranian foreign minister, said the attack was “a blatant U.N. Charter violation” and claiming it had been “done at Israel’s behest to drag Europe into its war.”

Araghchi added that he had told both the European Union’s top diplomat and Russia’s foreign minister to make clear that the attack “CANNOT GO UNANSWERED.”

Ukraine’s foreign minister, Andrii Sybiha, retorted, telling Iran it had “no standing to pretend to be a victim” because of its military support for Russia in its war with Ukraine.