Kabul ? Five NATO service members, including three Americans, were killed in Afghanistan on Monday, underscoring fears that casualties will rise as more foreign troops stream into the country.

Nevertheless, a new poll says Afghans are more optimistic than a year ago and think the Taliban are losing momentum.

The top U.S. commander in Afghanistan said he believed the rising presence of international forces was blunting the militants. Gen. Stanley McChrystal said the international force is on its way to convincing the Afghan people that it was there to protect them.

Afghans also think better days are ahead, according to the opinion poll, conducted last month before the suicide bombing that killed seven employees at a CIA base. About 40 percent of Afghans believe the Taliban insurgency is weaker than it was a year ago; 30 percent think it has gotten stronger and 25 percent believe the strength of the insurgency remains the same.

Nearly seven in 10 Afghans support the presence of U.S. forces and 61 percent favor the military buildup, according to the survey, the fifth commissioned by ABC, the BBC and ARD German TV since 2005.