The commander of U.S. and NATO forces in Afghanistan says he was surprised by the strength of the enemy when he arrived this summer.

Gen. Stanley McChrystal, in an interview to be aired Sunday on "60 Minutes" on CBS, says that in some areas of the country, the "geographic spread of violence is a little more" than he expected.

Today, military officials said five more U.S. troops have died in attacks in southern Afghanistan.

The rising death toll comes as the Obama administration considers whether to add more troops to the total that's already been growing by 21,000.

Most of the additional troops have been sent to the south, where they've been targeted by roadside bombs and ambushes as they try to take back areas controlled by the Taliban.

The U.S. is on track to have 68,000 troops in Afghanistan by the end of the year. The Pentagon says McChrystal is asking for as many as 40,000 more.

The influx comes as Afghanistan's government faces questions about the legitimacy of last month's election there.