US and allied forces carried out “large-scale” strikes against the Islamic State jihadist group in Syria on Saturday, the US military said, in the latest response to an attack last month that left three Americans dead.

Washington said a lone gunman from the militant group carried out the 13 December attack in Palmyra, which killed two US soldiers and a US civilian interpreter. The area is home to Unesco-listed ancient ruins and was once controlled by jihadist fighters.

“The strikes today targeted ISIS throughout Syria” and were part of Operation Hawkeye Strike, which was launched “in direct response to the deadly ISIS attack on US and Syrian forces in Palmyra,” US Central Command said in a statement on X.

The United States and Jordan carried out a previous round of strikes as part of the same operation last month, hitting dozens of Islamic State group targets.

The Palmyra attack was the first such incident since the overthrow of Syria’s longtime ruler Bashar al-Assad in December 2024.

The US personnel who were targeted were supporting Operation Inherent Resolve, the international effort to combat IS, which seized swaths of Syrian and Iraqi territory in 2014.

The jihadists were ultimately defeated by local ground forces backed by international airstrikes and other support, but IS still has a presence in Syria, especially in the country’s vast desert.

The US president, Donald Trump, has long been sceptical of American troops being in Syria, ordering their withdrawal during his first term but ultimately leaving them in place.

The Pentagon announced in April that the United States would halve the number of US personnel in Syria in the following months, while the US’s special envoy for Syria, Tom Barrack, said in June that Washington would eventually reduce its bases in the country to one.