Aquaman, Vol. 4 #1A

A Small World Incident
Craft from Oumland attack the city of Poseidonis, eventually cracking its dome. King Thesily convenes a council session to discuss the invasion, but the invasion interrupts it as Oumlandian troops pierce the dome. When this invasion becomes public knowledge the United Nations meets to discuss it. The Justice League's international charter stands in abeyance, so it cannot intervene. In California, Aquaman helps people trying to move a beached whale back to the ocean. She beached following the death of her calf. Sea life has begun behaving oddly. Aquaman heads to the disputed area between Atlantis and Oumland. There he incapacitates several Oumland submarines. From a commander, he learns their attacks are retaliatory, and seeks answers at Poseidonis, but before he reaches the city a torpedo destroys the city's dome, catching Aquaman and Vulko in the blast.
Release Date: 1991