The Defence Secretary has said the only way to resolve the conflict in Syria is by getting Russia to withdraw support for Syrian president Bashar al-Assad.
Speaking to ITV News, Michael Fallon said: "The campaign in Syria is much more complicated [than Iraq]. Complicated by the civil war and by Russia's determination to prop up Assad.
"It's only by getting Russia to withdraw its support for Assad, to join us in looking for a new political settlement there, that we can bring the civil war to an end, get the humanitarian aid in, and then move on Daesh terrorism in Raqqa."
Despite the international outcry over recent bombing campaigns in Aleppo, Mr Fallon said the UK's primary objective has been focused on Iraq.
"Pilots have been attacking Daesh infrastructure, particularly in eastern Syria, but of course their main focus in the last few months has been on the very successful campaign that's rolling now in Iraq - the liberation of Fallujah, of Ramadi along the Euphrates - and movement now up the Tigris towards Mosul."