US and allied forces have carried out “large-scale” strikes against the Islamic State jihadist group in Syria, 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 December 13 attack in Palmyra – home to Unesco-listed ancient ruins and once controlled by jihadist fighters – that killed two US soldiers and a US civilian interpreter.

“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, using an acronym for the jihadist group.

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 swathes of Syrian and Iraqi territory in 2014.

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

US President Donald Trump has long been sceptical of Washington’s presence in Syria, ordering the withdrawal of troops during his first term but ultimately leaving American forces in the country.

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

- Agence France-Presse