Former military leaders and a senior MP also warn RAF will not be able to sustain an effective bombing campaign because of a lack of aircraft.
Britain will have to put soldiers on the ground in Syria if it wants to defeat Isil even if David Cameron wins a parliamentary vote for airstrikes, one of the UK’s most senior military figures has signalled.
The stark message came as former military leaders and a senior MP warned the RAF will not be able to sustain an effective bombing campaign because of a lack of aircraft.
The Prime Minister is expected to ask MPs to back airstrikes in Syria within days but has insisted there will be no British troops on the ground.
Instead, he believes the estimated 70,000-strong armies of moderate Syrian forces can defeat Isil with the support of western airpower.