The UK's engagement in Iraq has moved beyond a solely humanitarian one, the Defence Secretary said, as RAF aircraft continued to fly reconnaissance missions to aid the fight against Islamic State extremists.
Michael Fallon told personnel taking part that it was likely to last "weeks and months" as David Cameron declared that British "military prowess" would have to play a part in pushing back the jihadist threat.
The Prime Minister said IS posed a "clear danger" to the UK's domestic security as he made clear the push would involve military and diplomatic efforts alongside ongoing work to help refugees fleeing massacres.
But he faced accusations from senior Church of England bishops that he had no "coherent or comprehensive approach" to Islamist extremism and was failing to protect Christians from persecution.
Mr Fallon revealed at the weekend that the RAF had now deployed the Rivet Joint surveillance aircraft alongside Tornado bombers to provide vital intelligence on IS movements across Iraq.
Kurdish Peshmurga fighters - aided by US air strikes - were reported to have regained control of the strategically-important Mosul dam in a success for the anti-IS forces.
Mr Fallon spoke to pilots and other service members during a visit to RAF Akrotiri in Cyprus, where the UK operation is based.
"There may well now be in the next few weeks and months other ways that we may need to help save life (and) protect people and we are going to need all of you again and the surveillance you are able to give us," he said.
"We want to help the new government of Iraq and Kurdish forces. We want to help them stop the advance of IS and stop them from being terrorised. This is not simply a humanitarian mission. We and other countries in Europe are determined to do what we can to help the government of Iraq combat this new and very extreme form of terrorism that by IS is promoting.”
Troops from the 2nd Battalion Yorkshire regiment were sent in to the Kurdish capital Erbil for 24 hours to prepare the ground for a possible rescue mission by Chinook helicopters.
Mr Cameron, who has resisted calls to recall Parliament to discuss the crisis, ruled out sending in ground troops "to fight or occupy" but insisted tough action would be required.