US Defense Secretary Mark Esper warned Thursday “all options are on the table” after a rocket attack in Iraq that killed three members of US-led coalition force, including two Americans.

Esper told reporters he spoke Wednesday with US President Donald Trump about possible retaliatory measures. “He gave me the authority to do what we need to do,” Esper said.

“Yesterday’s attack by Iranian backed Shia militia groups, consisted of multiple indirect fires that originated from a stationary platform and was clearly targeting coalition and partnered forces on Camp Taji,” Esper told reporters, according to Reuters.

Esper added, “Let me be clear, the United States will not tolerate attacks against our people, our interests, or our allies,” 

“All options are on the table as we work with our partners to bring the perpetrators to justice and maintain deterrence.”

Two Americans and a British soldier were killed Wednesday when rockets hit an Iraqi military base north of Baghdad, according to a US military official.

The two US nationals were a military contractor and a military serviceman reported the official, who spoke on condition of anonymity.