After arriving in Iraq on his first trip there as US defence secretary, Leon Panetta has said he will press his hosts on the fate of American military presence.
His unannounced arrival on Sunday came as a new diplomatic push was being made with the opening of another US consulate, in the northern Iraqi city of Irbil.
The US embassy in Baghdad - already the world's largest - has been expanding as the US transitions from a military to a civilian-led mission in Iraq.
The US is scheduled to withdraw all its remaining 46,000 troops from Iraq by the end of this year, under the terms of a bilateral security pact.
Panetta told the US congress last month that Iraq's government might eventually ask some US forces to remain beyond 2011.
But he was cautious in his comments to reporters on Sunday in Afghanistan, just before departing for Iraq.
Asked whether he would encourage Iraq to ask some US forces to stay, Panetta said: "I'll encourage them to make a decision so that we'll know where we're going".
The US might find it difficult to pursue its objectives in Basra, home of Iraq's only port and the country’s commercial hub.
The governate's local council recently passed a resolution to keep the US out of the province and called for its diplomatic mission to be reined in.
Hussein Ali, a Basra council member, told Al Jazeera's Rawya Rageh that it was unacceptable that its [US] mission should have 16,000 members.
He equated it to "another kind of occupation" and said ties should only be maintained with any of its occupiers once an apology and reparations for war damages were made.
That kind of mistrust, although widespread, was not shared by everyone in the city's streets as our correspondent discovered.
The question of US military presence is a tricky one for the mainly Shia coalition government of Nouri al-Maliki.
A powerful group in al-Maliki's coalition - headed by Muqtada al-Sadr, the Shia Muslim leader - opposes a continued US military presence.
Al-Sadr's bloc has threatened to escalate protests if US troops stay on.