The attack on Kuwait was the latest flare-up to shake the fragile ceasefire reached last month between the U.S. and Iran.
Kuwait had earlier announced an attack on its territory, and Iran announced it had retaliated after strikes earlier in the week on a U.S. base in an Gulf state it did not name.
The Iranian strike came after, earlier in the week, the U.S. said it had struck Iranian missile launch sites, minelaying boats and attack drones it said posed threats near the blockaded Strait of Hormuz.