The three American F-15E planes were accidentally shot down by Kuwait's air defenses, according to a statement from the US military command Centcom.
"Kuwait has acknowledged this incident and we are grateful for the efforts and support of the Kuwaiti forces in this ongoing operation," it said.
The downing reportedly took place near a US air base early on Monday Swedish time. For a few hours it was unclear why the aircraft crashed. Videos showing a plane in flames falling in a spiral-like trajectory, and footage that appears to show a pilot ejecting with a parachute, were published by news channels including CNN.
Shortly afterwards, Iran confirmed that it had attacked the base.
"Robot units belonging to the army's ground and naval forces in different locations have attacked the US Ali al-Salem base in Kuwait," a statement from the Iranian military said.
A total of 15 cruise missiles were used, and "enemy ships" in the northern Indian Ocean were also attacked, according to the statement.
The region has been shaken by attacks and counterattacks following the major Israeli and US attack on Iran that killed the country's supreme leader, Ali Khamenei.
