Conflicting purpose and intent? Or merely a difference in emphasis and nuance? Mr Blair has been a model of clarity from the outset. "We were with you at the first," he told the US from the platform of the Labour conference last week, and "we will be with you to the last".
In the same spirit, on Monday night in the Commons, the Prime Minister declared that Britain is "in this for the long haul". Amid strong signals that Washington already had Iraq in its sights Mr Blair seemed to prepare Britain, too, for military action beyond that currently directed against the Taliban regime and Osama bin Laden and his network. "Even when al-Qaeda is dealt with, the job is not over. The network of international terrorism is not confined to it," he declared, in clear warning of other enemies to be found and fought.
Yet just six days into battle there suddenly appears confusion and doubt. On Wednesday President Bush was in Blairite mode, drawing "a line in the sand against evil ones" wherever they might be found. Mr Blair, meanwhile, was seeking to reassure the Islamic world that the US was not about to extend its bombing campaign to Iraq. No such step would or could be taken without "absolute evidence" of complicity which, Mr Blair confirmed, did not exist.
Somehow this translated into compelling evidence of potential divergence between the US and her strongest ally. The BBC's 10 o'clock bulletin on Wednesday night brought first-hand news from Mr Blair's camp in the Oman to the effect that it was "not inconceivable" that the US could push for a strike against Iraq and that Mr Blair would tell the President to count him out.
Just minutes later, however, Mr Blair popped-up on BBC 2's Newsnight programme and declined the opportunity to commit himself either way. This speculation about future war aims, he suggested, was "a hare", got up-and-running by the programme's respected political editor.
She promptly countered that Mr Blair could easily shoot-it-down. He conspicuously refused to do so.
Similarly, yesterday, the Foreign Secretary, Mr Jack Straw, left the door ajar. Echoing the US Secretary of State, Mr Colin Powell, the Foreign Secretary maintained the British government was not "at present" contemplating action beyond Afghanistan.
He repeated there was no evidence linking Iraq to the September 11th atrocities, while allowing that "if circumstances change then we change". Mr Straw might otherwise have borrowed that other favourite political device and simply ruled nothing in or out. Authoritative Whitehall sources yesterday confirmed this is in essence Mr Blair's position.
Specifically they confirmed he had not ruled out action elsewhere, or made that so contingent upon international support as to render the prospect negligible.
The sources stressed the importance of sustaining the international coalition in aiding the present "first phase" of the assault on global terror.
They also acknowledged that, further down the line, allied actions start to become more problematic if the coalition fragments. However, the rules for such action would be the same as those applied in the case of bin Laden. Is there evidence? Is it (the proposed action) legal in terms of international law? And is it likely to be effective? So - if the Americans produce the evidence? Would Mr Blair - who many Americans say they would vote for if only he could run - refuse the President? Having warned that the terrorists already have Britain in their sights? And knowing that the leader of his domestic opposition is the supreme Atlanticist?
As the BBC divined, it is not inconceivable. Nor is it very likely.