Lord Richards, the former head of the armed forces, says the UK and its allies may eventually have to deploy ground troops to defeat the so-called Islamic State.
"Air power alone will not defeat Isis," he told ITV News.
Asked what whether ground troops were needed, he replied: "It could include boots on the ground."
David Cameron has said the UK is committed to working with the US to "destroy" the so-called Islamic State group in Iraq and Syria.
The Prime Minister told NBC that he wanted the UK to take more action but that he would need to "take Parliament with him".
"Look, we know that we have to defeat Isil, we have to destroy this caliphate, whether it is in Iraq or in Syria," Mr Cameron said.
"That is a key part of defeating this terrorist scourge that we face.
"I want Britain to do more. I'll always have to take my parliament with me. We're talking and discussing at the moment, including with the opposition parties in Britain, what more we can do.
"Be in no doubt, we're committed to working with you [the US] to destroy the caliphate in both countries."
David Cameron is in the Midlands today to set out a five-year plan to crush home-grown extremism.
The Prime Minister is vowing to tackle the "failures of integration" that left young Britons attracted to the self-styled Islamic State and other fundamentalist causes.
It is believed that around 700 British Muslims have travelled to Syria to join IS, with half since returning and posing a domestic terrorist threat.
Liz Kendall told a Mail on Sunday journalist to "f*** off" when she was asked how much she weighed during an interview.Read the full story ›
Carly Lovett of Gainsborough was one of thirty Britons killed in the Tunisian terrorist attack on June 26th. Her funeral is being held at All Saints' Parish Church.
Lively debate following the Chancellor's Summer budget. What's it in for people living in the Midlands?
Hear the views of Conservative MP Alan Duncan, Labour's Valerie Vaz and Liberal Democrat peer Lord Brian Paddick.
The Leader of Nottinghamshire County Council Councillor Alan Rhodes has issued the following statement on Toton becoming the preferred option for a HS2 station in the East Midlands.
“Nottinghamshire County Council has always been fully committed, 100 per cent, to Toton as we believe that a hub there would serve both Nottingham and Derby,"
“Toton would provide excellent overall connectivity for Nottinghamshire as a whole – including places to the north of the county like Kirkby and Mansfield – and bring enormous economic benefits, as well as improving travel time for passengers.
“Bringing HS2 to Nottinghamshire, combined with the dualling of the A453, will help make our county a place where businesses can flourish.”
The final decision on where the East Midlands station will be built will be made by Transport Secretary Patrick McLoughlin MP, who will set out how the Government plans to take Phase Two of the high speed rail project forward later this year.
The chairman of the HS2 project has confirmed that plans for a station in the East Midlands will be put forward for Toton.Read the full story ›
Labour leadership hopeful Liz Kendall has defended the party's interim leader, Harriet Harman after others attacked her for endorsing key Tory benefit cuts.
Liz Kendall said it was essential that the party showed that it had changed if was to regain the trust of voters.
She said "People said to us 'We don't trust you on the money, we don't trust you on welfare reform.'
If we are going to oppose things we have to put something else in its place, because if we carry on making the same arguments we have done over the last five years we will get the same result.
"We have to put forward a different credible alternative and Harriet was absolutely right to say that."
With the Liberal Democrats wiped out across the Central region in the General Election, there's a mountain to climb for the party to put itself back into the political landscape.
With the resignation of Nick Clegg, it left the party leaderless, but now the two contenders to replace him are trying to drum up support across the Midlands and put the Liberal Democrats back in the spotlight.
Gareth Owen has been to a recent hustings event in Stratford to speak to the two men who think they've got what it takes to lead the Lib Dems.