Two US Marines have been killed in southern Afghanistan, a military spokeswoman said Tuesday.
The spokeswoman said the two were killed in a "hostile incident" in the southern Helmand province on Monday. She spoke on condition that she not be identified because she wasn't authorized to release the information.
Some 4,000 Marines are pushing through Helmand province in the biggest Marine operation in Afghanistan since the ouster of the Taliban from power in 2001.
The region is the world's largest opium poppy producing area, and the Taliban's heartland.
Taliban fighters have planted dozens of roadside bombs in the region, one of the greatest threats to troops operating there.