US President Barack Obama (R) is greeted by Lt. Gen. Mark Milley upon his arrival to attend a memorial service in Fort Hood in Killeen, Texas April 9, 2014. Last week, Army Spc. Ivan A. Lopez killed three and injured 16 others at Fort Hood before taking his own life. The shooting was the second deadly rampage at the base, one of the largest US Army posts in the country, in five years. It raised questions about protecting soldiers at home and caring for troops battling mental illness, such as Lopez. [Photo/Agencies]