Several anti-Taliban Afghan fighters were also killed during operation which began on Friday and could run the rest of the week, Defense Secretary Donald Rumsfeld said during a press briefing.
Pentagon spokesperson Victoria Clarke had earlier called the fighting “the largest military operation we have been engaged in thus far and in combat, the most loss of life.”
At least eight U.S. troops were killed by enemy fire in two separate helicopter incidents on Sunday.
An official who asked not to identified told Reuters that at least seven troops were killed and ten were injured when enemy fire brought down an Army special forces MH-47 Chinook helicopter south of Gardez.
MH-47 helicopters can carry as many as 32 troops and crew, but there was no immediate information on how many were aboard the helicopter that went down.
This incident marks the first time a U.S. aircraft was downed by enemy fire since the war campaign began five months ago.
In a second incident, at least one U.S. soldier died when a rocket-propelled grenade hit a separate helicopter. The chopper made a so-called “hard landing” and then managed to take off again.
The soldier may have died after falling out of the helicopter in its abrupt landing, Rumsfeld told reporters today.
The ninth soldier, who was killed Saturday, was identified by the Pentagon as Army officer Stanley L. Harriman from North Carolina.
Nearly three dozen U.S. troops have been wounded since the battle with suspected Taliban and al-Qaida forces began on Friday, said Clarke.
Those injured were evacuated from the scene and half of them have already returned to the battle, Rumsfeld said.
The Pentagon announced it would consider sending more troops into the region while continuing its aerial campaign.
“This will not be the last such operation in Afghanistan,” said Rumsfeld.