A US military team has arrived in the Liberian capital Monrovia to assess how best to bring stability to the war-ravaged West African country.
The team will assess how to bring peace to Liberia
The 20-strong group of military civil affairs specialists is being seen as a possible forerunner of a larger US peacekeeping force.
But the US State Department has stressed that no decision has yet been made about whether to commit troops to a peacekeeping mission.
Tens of thousands of people in Liberia have been displaced since fighting for Monrovia broke out between government troops and rebels, and aid agencies have warned of a humanitarian crisis.
The World Health Organization has made an urgent appeal for funds and supplies to tackle a serious outbreak of cholera and other diseases.
Talks between the government and rebel groups continue in neighbouring Ghana, with mediators setting a target of 15 July for a transitional government.
Liberia's President Charles Taylor - indicted by a UN-backed tribunal on war crimes charges - has agreed in principle to leave the country following demands from US President George W Bush for him to quit.
But he said he would not accept an offer of asylum in Nigeria unless an American-led military force was in place.
The West African regional body, Ecowas - which had earlier agreed to send 3,000 peacekeepers to Liberia - has also been urging Washington to lead such a force.
On Monday, the US team landed at the heavily-fortified US embassy compound in Monrovia.
The commander of the force, Captain Roger Coldiron, said: "We are here to see what we will need to bring with us to provide humanitarian assistance."
"I am not here to assess the military situation, but I am here to assess the security situation."
The team, which includes experts in water purification, preventive medicine,
construction and logistics, will visit camps housing refugees from Liberia's war.
They arrived ahead of President Bush's five-day African tour which begins on Tuesday to promote his $15bn anti-Aids programme for Africa and a $100m anti-terrorism initiative.
The BBC's correspondent in Liberia, Mark Doyle, says President Bush clearly wanted to send a message ahead of his own arrival on the continent that he is concerned about Liberia.
But our correspondent says that Washington does not need to send an assessment mission, adding that US diplomats in Monrovia can literally see the humanitarian disaster on their doorstep by peeking over the high walls of the US embassy.
Mr Taylor accepted the offer of asylum from Nigerian President Olusegun Obasanjo, although he gave no indication of when he would leave.
Our correspondent says the Nigerian leader and other West African leaders seem to fear the creation a security vacuum if Mr Taylor leaves ahead of the arrival of a stabilisation force.
"We believe that it is not unreasonable to request that there be an orderly exit from power," Mr Taylor said at a joint press conference with the Nigerian leader, who arrived in Monrovia to discuss the offer.
The UN is in principle opposed to the exile option because it would mean Mr Taylor avoiding prosecution at the UN-backed war crimes tribunal in neighbouring Sierra Leone for allegedly supporting rebels responsible for widespread atrocities.