Tehran considered attacking a seaport in Ukraine in revenge for strikes on an Iranian ship heading for Russia, but a flurry of diplomacy has calmed the situation for now.The incident is the latest example of how the two wars are beginning to merge in a sign of increasing global instability.It comes after Ukraine, which has accused Iran and Russia of supporting each other’s military operations, struck an Iranian commercial cargo ship in the Caspian Sea on Saturday, killing a civilian sailor.The Islamic Republic vowed to retaliate. Some people briefed on intelligence said that they expected Tehran to fire a ballistic missile with a small warhead at Ukraine, to make a symbolic gesture but cause relatively little damage, according to The New York Times.Other officials said the target was likely one of Ukraine’s Black Sea ports. Any missile fired from Iran into Ukraine would be a dramatic escalation and risk triggering a wider conflict, given the tensions between the two nations over Tehran's alliance with the Kremlin.Islamic Republic officials said they hoped the conflict would end with their retaliatory attack, but Western officials warned that it was hard to predict how Ukraine would respond.