Death, desertion and injuries are making it difficult for Afghanistan's military to keep enough soldiers in the field to take over from departing international forces. By most accounts, the Afghan National Army should number at least 250,000 men to succeed in combatting the insurgency. But according to one U-S study, the force could never grow larger than 100,000, because it loses 42 percent of its men every year due to desertion and non-reenlistment. Another problem has been drug abuse, with at least 50 percent of Afghan soldiers found to be using drugs. Al Jazeera's Jennifer reports from Kabul.