A U.S. helicopter on a Special Forces mission in northern Afghanistan was forced down by bad weather Friday, but the crew was lifted out safely by a second helicopter on the same mission, Pentagon officials said.

Navy Rear Adm. John D. Stufflebeem told reporters that freezing rain was hampering efforts to fly additional U.S. Special Forces troops into Afghanistan to locate targets for U.S. warplanes and assist rebel units battling the ruling Taliban militia and the al Qaeda terrorist network.

It was to help train the rebel militias, as well as assist in spotting targets for U.S. warplanes, that the Pentagon has been trying to deploy small teams of special operations forces to augment the two dozen or so already in northern Afghanistan. But the insertion has been slowed by sub-freezing temperatures that have grounded the helicopters used to ferry the commandos to landing areas inside rebel-held territory.