MARJAH - Marines moving by land from the north linked up with United States units that have faced nearly constant Taleban attack in the four days since they were dropped by helicopter into this insurgent stronghold in southern Afghanistan.
US artillery fired non-lethal smoke rounds to disperse Taleban fighters in Marjah - the first time cannons have been used in the fight to drive the militants from their logistical and opium poppy-smuggling base.
Commanders refused a Marine request to fire deadly high-explosive rounds because the unit on the ground could not be sure civilians weren't at risk.
The linkup between the two Marine rifle companies and their Afghan Army partners will enable the US to expand its control in Marjah, Helmand province.
Lima Company of the 3rd Battalion, 6th Marines moved through fields of hidden bombs and booby traps and braved heavy sniper fire to join up with the same battalion's Kilo Company, which was airdropped into the town in the first hours of the operation on Sunday.
Lieutenant Gordon Emmanuel, a platoon commander in Kilo Company, said the Marines landed without encountering Taleban fire but came under sustained attack as they fanned out from the landing zone.
A Taleban spokesman, however, claimed that insurgents retain control of the town and that coalition forces who "descended from helicopters in limited areas of Marjah" were now under siege.
Spokesman Tariq Ghazniwal invited foreign journalists by email to visit Marjah, saying the trip would "show who have the upper hand in the area".
About 15,000 Nato and Afghan troops are taking part in the big offensive around Marjah, which has an estimated 80,000 inhabitants and was the largest southern town under Taleban control.
Nato hopes to rush in aid and public services as soon as the town is secured to try to win the loyalty of the population.
But a top Taleban commander, Mullah Abdul Razaq Akhund, dismissed the offensive as Nato propaganda and said on the group's website that Marjah was militarily insignificant. He said the main goal of the offensive was to "restore the place of the defeated military general in Afghanistan," General Stanley McChrystal, "even taking over a small village in Helmand temporarily and showing it to the Western world via video."
Nato said a service member taking part in the Marjah operation was killed by a roadside bomb yesterday - the third confirmed death among international forces since the attack on the town began.
An American and a Briton were killed on Sunday. Afghan military spokesman Lieutenant Mohammad Esah said one Afghan soldier died.
US officials said Taleban resistance in Marjah seemed more disorganised than in previous days, when small teams of insurgents swarmed around Marine and Afghan Army positions firing rifles, machineguns and rocket-propelled grenades.
But insurgent snipers hiding in haystacks exchanged fire with Marines and Afghan troops as they swept south.
Insurgents tried but failed to shoot down an Osprey aircraft with rocket-propelled grenades as Cobra attack helicopters fired missiles at Taleban positions.
Marines and Afghan soldiers continued house-to-house searches, removing bombs and booby traps.