The troops, including a 150-strong rapid reaction force, flew into Monrovia’s Robertsfield airport using nine helicopters, while four gunship-helicopters protectively circled overhead.

The US soldiers are to join West African peacekeepers in taking control of the port that the rebels are to vacate during the day for facilitating the arrival of much-needed humanitarian aid.

“I don’t expect any trouble with the deployment today,” said John Blaney, the US ambassador to the war-ravaged country.

Blaney said the rebels of the Liberians United for Reconciliation and Democracy (LURD) had given several guarantees and the port-takeover would be smooth.

“We expect this to be done peacefully,” he added.

Monrovia’s port is a gateway for food and humanitarian supplies to the city, where about 450,000 displaced people are living on the edge amid acute shortage of food, water and medicines.

LURD rebels, after vacating the city’s port, are to withdraw beyond the city limits.

'I don’t expect any trouble with the deployment today'

US ambassador to Liberia

But the arrival of US troops was preceded by sporadic shooting around one of the key bridges.

Rebels said they had been attacked, but the government said it was just looters. But the firing raised tensions, nevertheless.

“We are prepared to leave now but if they attack us, we will attack back,” rebel commander Small Dennis said.

But amid the ominous warning, battle-scarred Monrovia enjoyed a rare day of hope after US troops bolstered peacekeeping efforts.

Washington had earlier laid down the departure of Liberian President Charles Taylor as an essential pre-requisite before its troops could arrive in Liberia.

Taylor stepped down from power and went into exile in Nigeria on Monday. His exit revived hopes of ending Liberia’s 14-year long civil war.