The US carried out military strikes on five targets of an Iranian-backed militia in Iraq and Syria overnight. The US blamed the militia for launching a rocket attack that killed an American defense contractor on a military compound near Kirkuk on Friday.
US Defense Secretary Mark Esper said strikes had been successful and the pilots and aircraft had returned safely.
"The Department of Defense took offensive actions in defense of our personnel and interests in Iraq by launching F-15 Strike Eagles against five targets associated with Kataeb Hezbollah, which is an Iranian sponsored Shiite militia group," Esper said.
Esper said the targets included three in western Iraq and two in eastern Syria "that were either command-control facilities or weapons caches for Kataeb Hezbollah." The group is backed by Iran but separate from the Lebanese Hezbollah.
An Iraqi source known as the Popular Mobilization Forces said the strike killed at least 19 of the Kataeb Hezbollah members.
US Secretary of State Mike Pompeo said the Hezbollah attacks had been going on for weeks and it wasn't the first time the Iraqi base had been hit.
"What we did was take a decisive response that makes clear what President Trump has said for months and months and months, which is that we will not stand for the Islamic Republic of Iran to take actions that put American men and women in jeopardy. We will always honor that commitment to take decisive action when that takes place," Pompeo said.
"We continue to demand that the Islamic Republic of Iran act in a way that is consistent with what I laid out back in May of 2018 for what it is that we expect Iran to do, so that it can rejoin the community of nations," Pompeo said.
The US maintains around 5,000 troops in Iraq at the invitation of the Iraqi government, based there to fight the Islamic State.
Following the operation both Esper and Pompeo flew to Palm Beach, Florida to brief President Trump. Esper said they had discussed other options that were available.
"I would note also that we will take additional actions as necessary to ensure that we act in our own self-defense and we deter further bad behavior from militia groups or from Iran," Esper said.