Since the fall of Saddam Hussein more than two decades ago, the US has had a near-continuous military presence in Iraq... until now.
The last troops have been withdrawn, ending a process started by Joe Biden and endorsed by Donald Trump. But the timing of the departure has been questioned - with the US still at war with Iran.
According to Iraqi security experts, the withdrawal could give Tehran and its proxies free rein, while also risking a comeback from the Islamic State terror group.
So, why have Americans decided to leave Iraq now? And what will it mean for the future of the country - and stability of the wider region?
Niall Paterson is joined by Sky's military analyst Robert Clark, who served in the British military in Iraq and Afghanistan.
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