The shooting-down of a Syrian jet by the United States is believed to be the first air-to-air kill by a manned US aircraft since 1999.
Despite Hollywood blockbusters showcasing aerial dogfights, they have almost vanished from modern warfare.
In the 20th Century, skilled pilots who clocked up kills were often referred to as aces.
The US considers a pilot with at least five confirmed kills to be an ace – but no serving pilot holds the title.
What was the lesson of the Gulf wars?
A report published by the Center for Strategic and Budgetary Assessments (CSBA) in 2015 found just 59 kills since the 1990s – the large majority of which were in the First Gulf War.
Later that year, when Turkey shot down a Russian Su-24 plane along the Syrian border in a rare conflict, it sparked an international diplomatic row.
“The era of dogfighting is largely over,” says Justin Bronk, a research fellow at the Royal United Services Institute, specialising in combat airpower.
“After the totally lopsided kill-to-loss ratio attained by the US Air Force and US Navy during the First Gulf War, it is a very rare thing for regimes under attack by the US and its allies to send fighters up in defence – since they know how it will end.”
In that war in early 1991, Iraq lost 33 planes to coalition forces. In return, they shot down just one coalition F-18.
That lesson led many countries to abandon competition with the US and its allies.
“Even in the latter stages of the First Gulf War, many Iraqi pilots chose to fly their aircraft to Iran to escape certain…