MARJAH, Afghanistan, Feb. 13 (UPI) -- British, U.S. and Afghan troops began house-to-house searches Saturday in the Taliban stronghold of Marjah, commanders said.
The NATO-led force had achieved its first-day objective, seizing critical positions and encountering little resistance, The New York Times reported. One British and one U.S. soldier were reported killed.
Resistance became stronger as NATO troops spread out across the city, hinting fighting would be more violent in the coming days, the newspaper said. The door-to-door search of the city for militant fighters, weapons caches and concealed bombs is expected to take five days.
Taliban fighters said they were retreating temporarily to safeguard civilians as more than 15,000 U.S., British and Afghan troops pushed into the densely populated Marjah region of Helmand province, the BBC reported.
"Operation Moshtar" -- the Dari word for "together" -- is the largest NATO-led offensive against the Taliban since 2001.
Hours after the operation began, 11 Taliban bases had been captured and an estimated 70 percent of Marjah appeared to have been cleared of Taliban fighters, though the roads, fields and buildings ahead were expected to be booby-trapped with bombs, The Times of London reported.
At least five members of the Taliban had been killed, the BBC said.
The success of the operation will be determined by whether NATO-led forces can establish lasting peace in the area and establish stable governance in central Helmand, authorities said. One-thousand Afghan police officers were expected to arrive Sunday in Marjah, the Times reported.
Marjah has long been a Taliban stronghold and is key to a lucrative network of opium smuggling. The area's prime agricultural crop is poppies used to make opium and heroin.