The US says its military has carried out a 'massive strike' against the Islamic State group (IS) in Syria, in response to a deadly attack on American forces in the country.

Defence Secretary Pete Hegseth said Operation Hawkeye Strike was aimed at eliminating IS 'fighters, infrastructure, and weapons sites'.

Fighter jets, attack helicopters, and artillery hit multiple targets in central Syria, US officials informed CBS, the BBC's media partner in the US. Aircraft from Jordan were also involved.

President Donald Trump later asserted, 'we are striking very strongly' against IS strongholds, following the December 13 ambush in Palmyra that killed two US soldiers and a US civilian interpreter.

In a post on X, Hegseth remarked, 'This is not the beginning of a war - it is a declaration of vengeance... If you target Americans - anywhere in the world - you will know the United States will hunt you down.'

The US Central Command (Centcom) stated that 'US forces have commenced a large-scale strike' against IS, promising more information soon.

Following the strike, Trump emphasized that the US is making significant retaliatory efforts on those responsible for the attacks.

The UK-based Syrian Observatory for Human Rights reported that IS positions near Raqqa and Deir ez Zor were targeted, resulting in the deaths of a prominent IS leader and several fighters.

The attack comes after an IS gunman ambushed US forces in Palmyra, taking the lives of two servicemen and injuring three others, an operation where the Syrian president reportedly has no control.

Centcom has confirmed that IS remains active in the region with estimates of 5,000 to 7,000 fighters still in Syria and Iraq, despite their territorial loss in 2019.

US troops have maintained a presence in Syria since 2015 to assist local forces in combating IS.