"This strike was taken in self-defense. No civilians were harmed. No infrastructure or facilities were struck," the official said in a statement.

It targeted a leader of Harakat al-Nujaba -- a pro-Iran armed organization in Iraq -- who was "actively involved in planning and carrying out attacks against American personnel," the official said, adding that it also killed another of the group's members.

The strike comes amid heightened regional tensions linked to the war between US ally Israel and Iran-backed Hamas militants in the Gaza Strip.

The latest round of the Israel-Hamas conflict began when the Palestinian militant group carried out a shock cross-border attack from Gaza on October 7 that killed about 1,140 people, according to an AFP tally based on Israeli figures.

Following the attack, the United States rushed military aid to Israel, which has carried out a relentless campaign in Gaza that has killed at least 22,438 people, according to the Hamas-run territory's health ministry.

Those deaths have sparked widespread anger in the Middle East and provided an impetus for violence against American troops in the region, who have faced a spike in attacks since mid-October.

The United States has around 2,500 troops in Iraq and 900 in Syria as part of the multinational coalition fighting the Islamic State jihadist group since 2014.