| NEAR MARJAH, Afghanistan
NEAR MARJAH, Afghanistan U.S.-led NATO troops launched an offensive on Saturday against the Taliban's last big stronghold in Afghanistan's Helmand province, a test of President Barack Obama's troop surge strategy.
The assault, the first since he ordered extra troops to Afghanistan in December, is the start of a campaign to impose government control on rebel-held areas this year, before U.S. forces start to withdraw in 2011.
"The offensive in Marjah has begun. Our company is preparing to secure key terrain to facilitate stability and security for the people of Marjah," Lt. Mark Greenlief of Bravo Company, First Battalion, Sixth Marines, told Reuters.
A dozen helicopters flew from south of Marjah and the first objective of U.S. Marines was expected to be taking over the town centre, a large cluster of dwellings.
The U.S. military said about 4,500 U.S. Marines, 1,500 Afghan troops and 300 U.S. soldiers were taking part in the offensive in Marjah district.
One local Taliban commander, Qari Fazluddin, told Reuters earlier some 2,000 fighters were ready to fight in the densely-populated area.
The safety of civilians may be the vital issue for NATO in one of the eight-year-old war's biggest offensives against the Taliban, which have re-emerged as a powerful fighting force since they were toppled by a U.S.-led invasion in 2001.
Any heavy civilian casualties would make it even more difficult for the American-backed Afghan government to win support in towns that have been held by Taliban insurgents.
NATO forces have decided to advise civilians not to leave their homes, although they have said they do not know whether the assault will lead to heavy fighting.
Most of the population of the area, estimated at up to 100,000, has stayed put.
Unlike previous military operations, the assault on Marjah has been widely flagged for months. Commanders say they hope this will persuade many fighters to lay down their arms or flee, reducing the eventual body count.
Residents have been afraid to leave their homes in fear of roadside bombs planted by the Taliban to slow the U.S. advance.
Marjah, an area of lush farmland criss-crossed by canals, has been a breeding ground for both insurgents and opium poppy cultivation for years.
Much may depend on whether the state can ensure long-term political and economic stability to erase the conditions that have encouraged militancy.