The head of the British Army has cast doubt on the practicality of UK ground troops joining any future international peacekeeping force in the Middle East.
Sir Mike said progress had been made in Iraq
Gen Sir Mike Jackson said commitments in areas like Iraq and Afghanistan meant he doubted it would be "sensible" to offer troops to such a force.
But he suggested it would be easier to supply air or maritime resources.
The success of any international force depended on all sides agreeing to it, he told BBC World Service's Newshour.
"Without consent by all concerned - that is, Israel, Lebanon itself and Hezbollah - such a concept would be very difficult to put into effect," he said.
"You would be actually entering Lebanon against - or without, shall we say - the authority perhaps of the Lebanese government or the acceptance by Hezbollah of this force."
On the subject of British troop participation in the region, Sir Mike told the BBC: "Whether, given our other commitments elsewhere, it would be sensible for the United Kingdom to offer a contingent, I am rather doubtful on that point...
"I think one should not make any assumptions about British participation on the ground."
Sir Mike explained that it was important military resources were not overstretched and personnel were ready to replace colleagues posted around the world.
"Some 20% of the British Army is deployed at this particular time, which means 80% are not," he said.
"But to keep 20% sustained over time, as we do, you need the others.
"So I think one should not make any assumptions about British participation on the ground.
"There may be an air or maritime dimension to this, which could be helpful."
Sir Mike indicated he was optimistic about the situation in Iraq.
"You can construct any scenario you like, and as black a one as you like," he said. "I do not go down that road."
"We've already spoken of the huge efforts which are being made to fully establish, train and equip the Iraqi security forces themselves. And the coalition has played a large part in assisting that training."
He also denied the US and British troops ran the risk of become the "middlemen in a civil war" in Iraq.
"I don't regard what is happening as a civil war," he said.
"There are not two formed armies, there are not two formed governments."
On the possibility of British troop withdrawals from Iraq, Sir Mike said it "would not be very clever" to set a fixed date.
"We always said that the degree to which coalition forces can run down in numbers is pretty much directly related to the capacity of the Iraqi security forces themselves to handle the situation."
He told the BBC he had been impressed by the "quality and the advances" the Iraqi army had made.
"You talk to the youngsters under training and they make it clear that they have joined so that they play their part in taking Iraq out of decades of oppression."
And he said British troops were well equipped to deal with the "difficult" situation in Afghanistan where an increased Nato presence "was bound to cause reaction" by the Taleban.