US-led NATO troops have launched a crucial offensive against the Taliban's last big stronghold in Afghanistan's most violent province and were quickly thrown into a firefight with the militants.
The assault is a test of President Barack Obama's ordered "surge" of extra troops to Afghanistan in December and the start of a campaign to impose government control on rebel-held areas this year, before US forces start to withdraw in 2011.
Within hours of the operation getting underway, US Marines battled Taliban militants in Marjah, in Helmand Province in the south.
Three US soldiers died after a roadside bomb attack in southern Afghanistan today,
NATO said in a statement. It was not clear whether they were killed during the offensive.
Like civilians in the district of up to 100,000 people, the Marines face the risk of being blown up by scores of booby traps the Taliban are believed to have rigged.
Marines engaged in a firefight with the Taliban after the US troops landed in helicopters near the town. They fired at least four rockets at militants who attacked from compounds.
At least one Marine was wounded by shrapnel.
The first objective of US Marines was to take over the town centre, a large cluster of
dwellings.
The safety of civilians may be the big issue in the NATO drive against the Taliban, which re-emerged as a fighting force since being toppled by a US-led invasion in 2001. Heavy casualties may ruin the Afghan government's chance of gaining more support.
NATO forces have advised civilians not to leave their homes, though it is uncertain how heavy the fighting will get.
"The international forces must adopt certain procedures and mechanism during operation in Marjah to protect civilians," Afghan President Hamid Karzai said in a statement.
The offensive began with waves of helicopters ferrying US Marines into the city in the early morning hours. British troops then flew into the northern part of the surrounding Nad Ali district, followed by tanks and combat engineering units.
"The first phase of the operation is proceeding very successfully. The Taliban have heavily booby-trapped the area, but there has not been any fierce fighting yet," Helmand Governor Gulab Mangal told a news conference.
"We have seized 11 key locations in the district and the resistance from the insurgents has been subdued."
The 15,000-troop operation was named Mushtarak, or together, perhaps to highlight that NATO and Afghan forces are determined to work closely to bring stability to Afghanistan.
Much of whether the apparent early success can translate into a more permanent solution to militancy may depend on whether the government can ensure long-term political and economic stability.