A U.S. service member was killed on July 18 in northern Iraq during a controlled detonation of unexploded ordnance from a downed Iranian attack drone, U.S. Central Command said.
Another service member was injured and continues to receive medical treatment for a "minor" injury, Centcom said.
The death came a day after an attack on a base in Jordan killed two U.S. soldiers and left another missing, the U.S. military said. Centcom said it had found "unidentified remains" after a search of the location of Friday's attack in Jordan and that "an examination process to verify the remains is ongoing."
Centcom said in a Saturday statement posted to X that it relaunched strikes against Iran and began a new wave of strikes at 7 p.m. ET for the ninth consecutive night.
The U.S. and Iran have exchanged strikes, and both sides have been accused of striking critical infrastructure; Washington reimposed its blockade of Iranian ports while Tehran declared the Strait of Hormuz closed and targeted U.S. allies in the region.
The U.S. death toll in the conflict has reached 17 after an American Navy pilot who went missing earlier this month was declared dead.
In Iran, at least 50 people have been killed and more than 500 injured in U.S. strikes over the past three weeks, the country's health ministry has said.
CENTCOM said in a statement on Sunday that it did not identify the victims and that a second service member suffered mild injuries during the detonation.
The death brought the number of U.S. service members killed since the United States and Israel launched their war on Iran to 17, and the war began on Feb. 28.
Iranian media said the U.S. carried out attacks near the city of Sirik in southern Iran and near Shadegan close to the border with Iraq, and an explosion was later reported in Abadan.
Iran's Atomic Energy Organization condemned a U.S. attack on the site of a nuclear power plant under construction in Darkhovin, and the International Atomic Energy Agency said it was investigating reports of an overnight attack and that the plant was in the very early stages of construction.
Iran carried out drone attacks on U.S. military assets and equipment at Kuwait's Al-Adiri camp and the Ali Al Salem airbase, Iranian state television said, and Kuwait's government said a desalination plant had been attacked for the second day running, causing a fire.
Bahrain's air defenses intercepted an Iranian attack, and sirens sounded in Jordan where the military said it shot down three Iranian missiles.
Reports suggest the highly explosive Iranian one-way attack drones called "Shaheds" can be produced at a cost of about $30,000 each, while the interceptors used to shoot them down can cost millions of dollars and do not always find their targets.
The conflict has killed thousands of people, mostly in Iran and Lebanon, and led to major disruptions to energy supplies and fears over global inflation.