A rocket attack in northern Iraq killed a contractor and US service member on Monday, in the deadliest attack over almost a year.
The rockets hit in and near a military air base occupied by the US-led coalition at Erbil International Airport.
Two US officials said the contractor who was killed was not American. The coalition said five other contractors were hurt, without elaborating.
The attack, claimed by a little-known group that some Iraqi officials say has links with Iran, raises tension in the Middle East while Washington and Tehran explore a potential return to the Iran nuclear deal.
Armed groups aligned with Iran in Iraq and Yemen have launched attacks against the United States and its Arab allies in recent weeks, including a drone attack on a Saudi airport and rockets against the US embassy in Baghdad.
Most of the incidents have caused no casualties, but have kept up pressure on US troops and US allies in the region in the early days of Joe Biden’s presidency.
Biden’s administration is weighing a return to the Iran nuclear deal, which his predecessor Donald Trump abandoned in 2018, that aimed to curb Iran’s nuclear programme.
A group calling itself Saraya Awliya al-Dam claimed responsibility for the attack on the US-led base, saying it targeted the “American occupation” in Iraq. It provided no evidence for its claim of being behind the attack.
US Secretary of State Antony Blinken said late Monday the United States was “outraged” by the attack.
In a statement, Blinken said he had reached out to Kurdistan Regional Government Prime Minister Masrour Barzani “to discuss the incident and to pledge our support for all efforts to investigate and hold accountable those responsible”.
Groups that some Iraqi officials say have links with Iran have claimed a series of rocket and roadside bomb attacks against coalition forces, contractors working for the coalition and US installations – including the embassy in Baghdad – in recent months.