By Jill McGivering
BBC state department correspondent
US officials are still tight-lipped about a political storm that has blown up without warning.
Manila's change of policy caught the US by surprise
They are saying as little as possible about what exactly the Philippine
government is planning and what impact a change of policy might have on its relationship with Washington.
The official line to every leaked report and fresh statement from Manila is simply: "We don't have precise clarification."
But while the officials are maintaining a discreet reserve, it is clear that there is frantic talking going on behind the scenes.
'The wrong signal'
American diplomats in Manila are talking to officials in the Philippine government at all levels, from President Gloria Arroyo to senior figures in the foreign and defence ministries.
Neither side is disclosing the nature of those discussions.
But if the US is struggling to persuade Manila to stand firm and not withdraw its troops early, its mission is starting to look doomed.
On Wednesday, US state department spokesman Richard Boucher told reporters he had no reason to doubt reports from Manila that troops would pull out early, before the planned date of 20 August, saying he didn't know what date they were leaving.
But he restated the US position clearly, repeating disappointment about the apparent change of position by Manila on concessions to hostage-takers.
"We think withdrawal sends the wrong signal," he said. "It's important for people to stand up to terrorists, and not allow them to change our behaviour."
Bolt from the blue
The frustration was clear. It is equally clear that the US has been embarrassingly wrong-footed by the developments of the last few days.
Senior officials in the state department have confirmed this apparent change of policy caught them by surprise.
Just last weekend, US Secretary of State Colin Powell had a one-to-one telephone conversation with President Arroyo.
Apparently there was no sign then that the president of the Philippines was wavering on her commitment to stand firm in the face of militant threats.
For the US, Monday's televised statement by the deputy foreign minister that Manila would withdraw troops "as soon as possible", along with a plea for the release of the captured Filipino lorry driver, came as a bolt from the blue.
The Philippine government has been under pressure to pull out
And it has left Washington struggling to regain lost ground ever since.
So far, US officials have been reticent too about the likely damage to the US-Filipino relationship, until this week a solid and mutually loyal partnership.
Asked on Wednesday about the impact, Mr Boucher said: "We'll have to see."
There is a lot at stake. In the past, the Philippines has been a staunch US ally in the war on terror, sharing intelligence and training.
They have also co-operated closely in trying to tackle Manila's own terrorist threat - its domestic Islamic militant groups with separatist ambitions and suspected links to the al-Qaeda network in South-East Asia.
Washington is bound to understand the political pressures its ally is facing.
The fate of Angelo de la Cruz has become a potent domestic issue.
The small contingent from the Philippines was due to leave Iraq soon anyway and numbers only about 50 non-combat troops.
Several thousand other civilian workers from the Philippines will still be employed by private contractors in Iraq long after the troops have left, whichever date they choose.
Their safety is of growing concern too.
But for Washington, action by a key ally which sends a signal to militants that hostage-taking works, is action they are desperate to forestall.
The uncertainty is whether they still can.