A mood of cautious optimism pervades the Pentagon as U.S. troops extend their control in Baghdad and jubilant Iraqis take to the streets.

The way Pentagon officials see it, the toppling of Saddam Hussein's statue in central Baghdad may be as historically momentous as the toppling of the Berlin Wall.

But there is still a sense of caution. As one senior military official put, "the hunt is not over until the head is on the wall", and he notes Iraqi leader Saddam Hussein's whereabouts and fate remain unknown.

Various rumors are circulating; that Saddam is dead, injured or alive, and at large. But intelligence sources say they do not think it likely the Iraqi leader is hiding in a foreign embassy, one of the latest rumors.

Defense officials have declined to say whether U.S. troops are under special instructions about what to do if they find Saddam.

But two known air-strikes, one this week in Baghdad, were clearly aimed at killing him, suggesting the coalition is not necessarily committed to taking him alive.