Former military top brass have raised warnings about the crisis in Iraq as David Cameron headed to a Cornish beach on his second holiday of the summer.
Former head of the Royal Navy, Lord West of Spithead, warned there is a "worrying" lack of clarity about the UK's strategy and a danger of "mission creep".
General Sir Richard Dannatt, former head of the British Army, meanwhile, insisted "the nation would expect" Parliament to be recalled to allow MPs and peers to debate Britain's growing involvement in the conflict and said it was "unwise" for the Government to publicly rule out British "boots on the ground".
Iraqi security forces have launched an offensive to take back the city of Tikrit, which has been occupied by Islamic State (IS) since June, following yesterday's victory in the retaking of the Mosul Dam from militants.
Britain is poised to provide weapons to Kurdish troops fighting the "murderous extremists" of IS in northern Iraq as well as continued humanitarian aid.
As the debate over Britain's role continued to rage, the Prime Minister was photographed sipping coffee with wife Samantha at Surfside cafe on Polzeath beach in Wadebridge.
Dressed casually, the couple appeared relaxed as they sat at a window table that overlooked a beach busy with holidaymakers.
Mr Cameron has insisted he remains in control during the holiday and is "always within a few feet of a BlackBerry".
Sir Richard, who was a defence adviser to the PM after he retired as chief of the general staff in 2009, warned that MPs and Lords would get "very frustrated" if they did not get to address the situation before Parliament sits again.
MPs are due to return briefly in September but peers will not have a chance to debate the issue until October.
Speaking from Cornwall, Sir Richard told BBC Breakfast: " I think there will come a point as this general set of circumstances unfolds, when Parliament needs to come back together, people need to have a full debate about it and express their point of view.
"I think the nation would expect that."
Lord West, former First Sea Lord, told the Daily Mail: "We need to be very certain of our ultimate aim and we don't seem to have great clarity of vision about what we are going to do there. It is very worrying.
" There is always a danger of mission creep. We need to be very clear on our game plan - what, at the end, is going to make our nation and the globe more secure.
"The problem with getting involved is there is no way you want to become fully involved. It would be a dangerous step to have troops on the ground.
"But you look at what the Islamic State is doing and it is incumbent to do something. We should use limited military capabilities: reconnaissance capabilities, intelligence, possibly airstrikes and using Special Forces to mark targets for firing from drones."
Mr Cameron has pledged that the UK will not be "dragged into a war in Iraq" but Labour has criticised the Government's strategy, claiming the British role in the crisis is unclear.
Earlier this month, the PM cut short a trip to Portugal to respond to the emergency and has insisted he will do the same again "instantly" if necessary.
"Wherever I am, wherever I am in the world I am always within a few feet of a BlackBerry and an ability to manage things should they need to be managed," he said yesterday.
Two British-chartered Airbus cargo flights landed in Erbil today carrying 45 tonnes of high-nutrition food and 515 family-sized tents.
International Development Secretary Justine Greening said: "The UK continues to deliver essential aid supplies to deal with the worsening humanitarian situation in towns across northern Iraq. These hundreds of DFID tents will provide families who have lost everything with decent shelter now, as well as during the colder winter months, and the high nutrition food we have flown to Iraq on behalf of the World Food Programme will provide nutrition for thousands of children.
"Many of these are the displaced Iraqis who managed to escape Mount Sinjar by walking many miles in searing heat. They have shown immense courage and been through unimaginable hardships. The UK is committed to supporting them."
Both flights set off from Dubai, where DfID has a sunstantial aid store. The Royal Air Force (RAF) has made seven successful air drops of aid over Mount Sinjar, including water containers, solar lamps and shelter kits.