Second, an enlarged American military presence in Syria would force Tehran to think twice before it further entrenches itself in the country.

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Third, without a military presence, the US will not be in a position to influence the development of events after the defeat of Islamic State. It will be left to Russia, Iran and, to a lesser extent, Turkey to determine the future of Syria. American allies in the region will be adversely affected by the nature of any outcome.

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Fourth, the continuing US military presence will prevent Islamic State from re-emerging in Iraq and Syria. No one should relate the group’s defeat in the battlefield with their ideological durability. They have already emerged elsewhere in the Middle East, North Africa, and Europe.

Fifth, nothing will deter the main antagonistic players in Syria – the regime of Bashar al-Assad, Russia, Iran and Turkey – other than a robust American military presence, sending a clear message that the US intends to play a weighty role in the search for a solution.

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Sixth, since the start of the conflict, the US – under both Barack Obama and Trump – has sent a clear signal that it has no geostrategic or security interest to be deeply involved in Syria’s civil war, merely providing marginal financial and limited military training to rebels in their fight against the Assad regime. This indecisive approach has been a dismal failure, it has marginalised the US while allowing Russia, Iran and Turkey to disregard America.

Dr Alon Ben-Meir, professor, Centre for Global Affairs, New York University