There are conflicting accounts of the location of the drone attack which killed three US servicemen.
US President Joe Biden says the attack took place in north-east Jordan, close to the Syrian border, suggesting the location was a US base called Tower 22, which is just across the border from the much larger US base at al-Tanf, in south-east Syria.
However, a Jordanian spokesman says the attack took place at al-Tanf, not on the Jordanian side.
The Americans have maintained the secretive al-Tanf base since 2016 (during the height of the campaign against the Islamic State group).
Between 100 to 200 US servicemen operate there, conducting counter-terrorist and counter-narcotics operations.
Tower 22 is described as an “advise and assist” mission to Jordan, but is clearly closely connected to nearby al-Tanf.
A drone attack on al-Tanf in mid-October seriously injured one American.
There have been other attacks in previous years, so this is not the first time this general area has been attacked (though if Biden is correct about the location, then this is the first recorded attack inside Jordan since 7 October).
Whether the latest attack represents an escalation by pro-Iranian militias in Syria or a continuation of routine tit-for-tat operations is not yet clear.
This attack comes just 10 days after the Jordanian air force carried out air strikes in south-west Syria, in what was described as a counter-narcotics operation.
