The SDF said the drone hit their commando training academy.
At least six fighters from the Kurdish-led Syrian Democratic Forces (SDF) died in a drone attack on the biggest US military base in Syria.
The SDF said the drone hit their commando training academy at the al-Omar oil field in Deir al-Zour province, in the east of the country, early on Monday.
It blamed militias backed by Iran for launching the drone from an area under the control of Syrian government forces nearby.
A group of Iraqi militias with ties to Iran said they attacked the base on Sunday.
The US military, which has about 800 troops in Syria to fight the Islamic State (IS) group, did not comment or report any casualties.
The SDF – which has held most of north-eastern Syria since it defeated IS there in 2019, with the help of a US-led international coalition – said in a statement that a one-way attack drone killed six of its “commando fighters” when it struck their academy around midnight on Monday.
It claimed that “Iranian-backed militias used the areas in Deir al-Zour controlled by the Syrian regime as a launch pad for the terrorist attack”.
The SDF denounced the attack and said it had the “right to respond suitably to the source”.
The Syrian Observatory for Human Rights, a monitoring group based in the UK, said that 18 SDF commandos were injured and seven killed in what it called the 108th militia attack on US bases in Syria since mid-October.
The Islamic Resistance in Iraq (IRI) – a group of Iraqi militias that Iran is believed to arm, train and fund – said it carried out a drone attack on Sunday “against the US occupation base in al-Omar oil field”.
The IRI has taken responsibility for many of the drone, rocket and missile attacks that have hit US troops in Iraq, Syria and Jordan since the war between Israel and Hamas in the Gaza Strip began. It says that they are a show of support for the Palestinian people.
The attacks include the drone strike on 28 January that killed three US soldiers at the Tower 22 base near the border between Jordan and Syria.
Iran denied any role in the attack, but the US thinks it made the drone and that the IRGC’s Quds Force, a branch of Iran’s Islamic Revolution Guard Corps (IRGC), co-ordinates the militias.
On Friday, the US warned that it was just the “start” of its response to the Jordan attack and hit more than 85 targets at seven sites in Iraq and Syria used by the IRGC and its allied militias.
The Syrian Observatory for Human Rights said the strikes in Syria killed 29 pro-Iran fighters. In Iraq, officials said 16 people died.
As tensions rise in the region, US Secretary of State Antony Blinken is in Saudi Arabia on a Middle East tour, his fifth since the Hamas attacks on Israel on 7 October.
Blinken will go to Egypt, Qatar, Israel and the West Bank later this week, urging officials to agree on a new deal to release Israeli hostages and to help avoid a worsening of the conflict.
