The 83-year-old political heavyweight said that a collapse of control in Iraq would lead to disastrous consequences that would drag the West back into the Middle East.
The diplomat also called for America to open dialogue with Iran, warning that a confrontation would occur without a negotiated solution to the stand-off over the Islamic republic's nuclear programme.
"We have to move at some early point to some international definition of what a legitimate outcome is -- something that can be supported by the surrounding states and by ourselves and our allies," Kissinger told BBC television from his Connecticut home.
"At some early point an international conference should be called that involves neighbours, perhaps the permanent members of the (United Nations) Security Council and countries that have a major interest in the outcome like India and Pakistan," the Nobel Peace Prize laureate said.
Kissinger was asked whether there was any hope left of a clear military victory in Iraq.
He replied: "If you mean by clear military victory an Iraqi government that can be established across the whole country that gets the civil war under control and sectarian violence under control in a time period that a political processes of the democracies will support, I don't believe that is possible."
He said the international coalition with troops deployed in Iraq had to redefine their course in the country.
"A dramatic collapse of Iraq, whatever we think of how the situation was created, would have disastrous consequences for which we would pay for many years and which would bring us back in one way or another into the region," he said.
Diplomatic relations between the United States and Iran have been frozen since 1980 and the United States believes Iran's uranium enrichment programme is ultimately aimed at producing fissile material for nuclear weapons.
"I believe America has to be in some dialogue with Iran," Kissinger said.
"It seems to me the fundamental problem is this: does Iran conduct itself as a crusade or as a nation?
"If Iran is a nation it should be possible to define a relationship in which Iran, together will all interested parties, contributes to stability in the region and plays a respected role.
"If Iran is a crusade that is trying to overthrow the international system as we know it, which is the way the Iranian president talks, then it will be extremely difficult to come to a negotiated solution and then down the road some sort of confrontation will occur."

Copyright AFP (Agence France-Presse), 2006