U.S. military officials say all four NATO troops killed in a helicopter crash in southern Afghanistan on April 19 were Americans.
Pentagon spokesman Captain John Kirby told reporters on April 20 that the Black Hawk helicopter went down in stormy weather after responding to a suicide attack in Helmand Province's Garmser district.
The NATO-led force earlier said four of its troops died in the crash, but did not release their nationalities.
Taliban insurgents claimed responsibility for the crash, saying on a website the aircraft was "shot down by a rocket attack by armed mujahedin fighters."
However, the Pentagon's Kirby said, "It appears that the weather was the principle cause."
Mohammad Islamil Hotak, a senior police officer in Helmand Province, also said there was "no proof" that the Taliban was responsible.
Earlier, Daud Ahmadi, spokesman for the governor of Helmand Province, said the helicopter crashed in heavy rain as it was bringing back Afghan police who were injured in a suicide attack in Gramsir district.
There have been a number of helicopter crashes in Afghanistan since the U.S.-led invasion in 2001, but the NATO-led force says they are rarely the result of Taliban fire.
With reporting by AFP and AP