Attacking Isis from the air would be “pointless, futile and a dangerous empty gesture" without boots on the ground, a senior Tory MP has said after David Cameron indicated his intention to win a Parliamentary vote on Syrian intervention by Christmas.
Julian Lewis, chairman of the Defence Select Committee, said trained and experienced military forces on the ground would be needed to make any air strikes in Syria effective.
The RAF is currently aiding Kurdish forces on the ground in Iraq by bombing Isis targets, but Mr Lewis said the same approach would not be effective in Syria.
"You cannot do this job from the air alone unless there is a credible ground force and I don’t mean just the Kurds who are only part of the picture," he told the BBC.
"There has to be a credible ground force which we are supporting with our air power.
"Otherwise it is a pointless, futile and a dangerous empty gesture. Apart from that it’s a great idea."
On Tuesday Mr Cameron promised to set out a "comprehensive strategey" for defeating Isis and said the case for military intervention in Syria had "only grown stronger" since Islamic terrorists killed 129 people in the devestating terror attacks in Paris on Friday.
But he will only go ahead with a vote in the House of Commons if he is confident of winning, Downing Street said.
Ministers will set out the plans to bomb Isis in Syria by the end of the month, meaning the first air strikes could be launched before Christmas.
He and other ministers have described as "absurd" the current situation where Britain is carrying out airstrikes on Isis in Iraq but not over the border in Syria.
The Government faces a tough battle to win a majority in favour of air strikes in Syria, with Jeremy Corbyn firmly opposed to military intervention.
He has ruled out the prospect of giving Labour MPs a free vote on the issue, a decision that was criticised by former front bencher Emma Reynolds, who said the leadership should allow Labour MPs to vote how they like "given the divergence of views that there are".
Meanwhile a report by the Royal United Services Institute has warned that that Britain may need to carry on air strikes against Isis for years to come, even if there is little prospect of delivering a knockout blow.
The military think tank said that without a wider political settlement in Syria, the UK could have to sustain its military campaign against the extremists "over a period of several years".
Even then, the report said, it is possible - "perhaps even likely" - that the operation will end without having achieved a "decisive strategic effect".
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