America is not gung-ho. It is a nation in fear, resigned to the coming war

The mood is one of grim determination. People are afraid, and are willing to take more pain in order to feel less afraid

Mr Shen from Guangxi drove me in from the airport. He was an enthusiastic man. Thirty years in America and still it thrilled him to cut across the lanes on Interstate 308, chuckling if another car honked its horn, and asking me if I realised how lucky we both were to be living in America. I told him I didn't live in the US but in Britain.

"Britain too rainy and small," he declared. Then he went on to say that he had no intention of going back to China. This was curious as I had never raised the subject. It struck me that Mr Shen was used to having long conversations with himself. I was simply another member of his passing audience.

Mr Shen resorted to a long recitation on the bounty of his American life. It is the extraordinary thing about the American taxi driver. Unlike most of their colleagues all over the world they rarely whine about their lot. I think it is because they always believe they are on the way to someplace better.

Mr Shen's good spirits helped to boost my own. After weeks of London rain and a 10-hour flight I was ready for the sunlight and the smell of the Pacific as we crossed the Bay Bridge to Oakland. It is made all the better because the East Coast and much of the South is snowbound. All day rosy-cheeked reporters have been popping up on the news channels chirping the usual banalities about the snow, light relief from the relentless coverage of the coming war with Iraq (which even the White House doves now seem to accept is inevitable).

This morning the news programmes gave strong play to research by the Pew Research Centre for the People and the Press, showing mounting anti-American sentiment in Arab countries. The executive chairman of the institute is none other than former Secretary of State, Madeleine Albright, who said she was "stunned" by the figures indicating high levels of support for suicide bombings across the Arab world. Mr Shen was worried about this. He loved America. He loved it so much I thought he would burst through the roof of the car, so much that he didn't want George Bush to attack Saddam and provoke an attack on American troops with weapons of mass destruction.

"What do you think Saddam does, eh? He like a rat cornered. This guy has nowhere to run, sir. He will spread his gas everywhere and our boys will be killed," Mr Shen said. Tomorrow I head for Chicago where it is several degrees below zero but today it is San Francisco and a different face of a country heading for war.

This is a city where America's nascent anti-war movement is strongest, with a tradition of liberal dissent. The local Congresswoman, Barbara Lee, was the only member of Congress to vote against giving the President wider powers to make war in the wake of the 11 September attacks. The place has the feel of the multi-cultural dream American politicians mythologise. On the notice board in the hotel lobby I saw that the Oakland Islamic Centre was having a conference. That was just a door or so away from a city judges convention. Upstairs in the bar the road crew and several musicians from what used to be known as the Grateful Dead were enjoying the first of many afternoon drinks. The atmosphere was as I'd always remembered it: easy, comfortable, the feel of a city at home with itself and not afraid to look the world in the eye.

When I first came to San Francisco more than 20 years ago, America was only starting to come terms with the horrors of Vietnam. Just up the road here was the airfield where the planes carrying troops to and from Vietnam used to take off and land. When I went to San Francisco, five years after the last choppers had left the roof of the US embassy in Saigon, the Army and Navy stores were full of surplus gear from that misbegotten war. Jimmy Carter was in the White House and there was a national mood that was profoundly cautious.

The national mood today is what the political writers like to call one of "grim determination". That means people are afraid, and are willing to take more pain in order to feel less afraid. Here in San Francisco there is a generalised feeling against war, but that is not true of the country generally. Americans will support Mr Bush when he decides the time is right to attack Iraq.

Like Mr Bush, they would prefer that one of Saddam's murderous colleagues would stage a coup, but they accept this is not likely. Dissenters are thin on the ground here. The septuagenarian parents of a friend of mine got a taste of this when they went to a dinner party in their home city of St Joseph, Missouri the other night. My friend's father had been a tail gunner on bombers over Germany during the last war and is nobody's idea of a "touchy-feely" liberal.

But like Mr Shen he worries about what a cornered Saddam might do, and about the effect of an invasion on the Arab world. The good folks at dinner in St Joe, Missouri thought he was letting down his country for even suggesting this. With 10,000 reservists about to be called up for duty the old tail gunner had touched a raw nerve. The ghost of Vietnam has not been laid entirely to rest, particularly among an older generation who know what it is like to attend the funerals of neighbours' children. They sense that war against Iraq might involve many more such funerals, but do not wish to be reminded.

So the mood is not gung-ho. I think "resigned" is the better description. Most people truly believe that Saddam and al- Qa'ida are part of the same project. It is not a view that the White House has done anything to discourage. The White House and Pentagon have been engaged in "mood altering" this week. The show of patience and engagement with the UN seems to be coming to an end. Consider this quote from Ari Fleischer, the voice of Bush: "Iraq has lied before and is lying now about whether they have weapons of mass destructions." This, days before the Iraqis were due to present their dossier.

Thus the stage is set for US, and presumably British, rejection of Saddam's promised list of his weapons programmes. The Bush administration hints darkly that it has solid intelligence that will confound any Iraqi claims of innocence. Meanwhile the inspectors are hustled for being insufficiently aggressive while being accused by Baghdad of acting as spies for the US and Israel. They should feel honoured to be so doubly damned but it must be doubtful now whether they will ever finish their mission. There is a sense that we are entering the endgame on Iraq.

In San Francisco they will come onto the streets if President Bush decides to attack Iraq. There will be thousands of demonstrators, but I doubt that they will count for much while a frightened national majority remains in favour of war. This doesn't make dissent a meaningless gesture: It simply means that fear, the single biggest consequence of 11 September, is the key to understanding the new America.

The writer is a BBC Special Correspondent