By Jon Leyne BBC State Department Correspondent

In much of the world, a lively debate is going on about whether the United States should attack Iraq.

The main line of debate is: what is the fastest way that we can have a successful invasion

Rear-Admiral Stephen Baker

In America itself, the debate has hardly started. But that could all change with the Senate Foreign Relations Committee's hearings on the issue.

The influential committee is hearing evidence from expert witnesses, but the Bush administration has declined to take part.

For President George W Bush recently, it has been a case of "Don't mention the war" - or at least, "Don't mention Iraq - just warn of the 'threat'".

"America must act against these terrible threats before they're fully formed," the president said earlier this month.

Evidence

While the warlike rhetoric continues, the idea of actually attacking Iraq is still not openly discussed by the administration.

Biden: the public should know about the options

Until now, there has been virtually no public debate on the issue in the US.

"This is just beginning to raise the issue, what's at stake here," said the chairman of the Foreign Relations Committee, Senator Joe Biden.

But Washington Post columnist Jim Hoagland says the Bush administration should be more forthcoming.

"I think the public is waiting for the administration to come forward with a clear and compelling case that it has concluded, with the evidence presented, that Saddam Hussein's regime represents a threat to American lives, to American interests, to regional stability and to global stability."

The other big question is not whether to go to war, but how to do it.

It is now more than a decade since former President George Bush senior celebrated his overwhelming yet indecisive victory against Saddam Hussein.

Split administration

So what are the military thinking this time round?

"I think the main line of debate is: what is the fastest way that we can have a successful invasion," says Rear-Admiral Stephen Baker, a veteran of the last Gulf War.

"How can we ensure absolute success as quickly as we can?"

But everything remains up in the air.

"There's clear division within the administration," Senator Biden says.

"I don't expect we're going to see any action on Iraq in terms of military action anywhere in the near term, meaning between now and November," he adds.

And even delaying beyond November would still leave the administration precious little time to mobilise both the American people and world opinion.