Mr Blair has just touched down at Andrew's Air Force Base.
Meeting Mr Bush tonight, and Kofi Annan tomorrow.
Sopme more info on RG movements:
WARPLANES ATTACK CONVOY
British warplanes are attacking a large column of Iraqi troops heading out of Basra as 5,000 Republican Guards are reported to be heading for a possible showdown with US Marines.
British radar picked up a convoy of some 70 -120 vehicles retreating from Basra on Wednesday evening.
The convoy is heading towards the al-Faw peninsula and the military says it could either be a counter attack by the Iraqi army to recapture lost territory or a retreat from Basra to avoid a limited uprising that began on Tuesday afternoon.
The Officer Commanding 40 Commando's battle room, Major Mick Green, said: "We have no idea why this column has come out at the moment.
"Their intentions or motives are totally unclear but they have adopted an offensive posture and do not want to surrender, so we have attacked them."
'Suicide'
Major Green added: "The inexplicable thing is why they have decided to move so much armour before darkness. To move tanks around in daylight is suicide."
The convoy is heading towards territory secured at the weekend by Royal Marines from 40 Commando.
It is thought the Iraqis may have felt the fierce sandstorms would have given their armour cover.
From the air, US Navy F-18 Super Hornets and RAF Harrier ground attack jets are dropping precision-guided munitions and cluster bombs.
And from the ground, the column is being pounded by 155mm AS90 heavy artillery from 3rd Regiment, Royal Horse Artillery, and 105mm light field guns from 29 CommandoRegiment, Royal Artillery.
A second group of around 1,000 Republican Guard vehicles containing up to 5,000 troops are heading south from Baghdad towards US Marines, American media reported.
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http://www.sky.com/skynews/article/0,,30000-12275999,00.html