A sharp increase in U.S. Army suicides is likely due to an increase in a range of stresses on soldiers both at home and in war zones, a top Army officer said Thursday.

A 15-month-study on the rise in suicides over the last two years found 160 suicides among active-duty personnel, 1,713 suicide attempts and 146 deaths from high-risk behavior, such as drug abuse, in the year ended Sept. 30, 2009.

The...