The trip will gauge support for further action on Iraq
US Vice-President Dick Cheney is London at the beginning of a two-week mission to Europe and the Middle East.
He says that his main purpose is to encourage countries in the Middle East not to harbour al-Qaeda and to assist America in its war on terrorism.
However, in what is the most extensive trip ever conducted around this region, White House officials say he will also be seeking the region's views on military action against Iraq.
Most of the heads of state Mr Cheney will be meeting were in power when he shuttled around the region 10 years ago, as secretary of defence gathering support for the first Gulf War.
He has remained in touch with many of them during the intervening years in places like Saudi Arabia and the Gulf states he is a trusted and known figure.
In fact, of the 13 countries he will be calling in on during his whistle-stop tour there is only one, Yemen, that he has never been to before.
Iraq campaign
His priority is to try to stop al-Qaeda cells regrouping in the region. He will offer American assistance in areas such as law enforcement and military training.
1. Somalia: Suspected al-Qaeda base
2. Yemen: Bin Laden's ancestral home
3. Sudan: Attacked by US missiles in 98
4.Iraq: Threatened by President Bush
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Detailed clickable map
Iraq is, of course, also on the agenda. The White House knows that Iraq's neighbours are troubled by the prospect of a military assault, but if they are convinced that America is serious about removing Saddam Hussein, they will probably acquiesce.
Mr Cheney will be sounding out what support, whether diplomatic or military, each country feels able to provide.
He admitted before leaving that he would be asked at every stop about the Israeli-Palestinian issue, but he does not appear to be touting any new initiatives.
The White House is sending its envoy, General Anthony Zinni back to the region, partly to deflect accusations that the US is not doing enough to bring Yasser Arafat and Ariel Sharon back to the negotiating table.