Some analyses suggest that at the current pace and size of American troop deployments to Iraq, the availability of suitable reserve combat troops could become a problem as early as next year. Robert Goldich, a defense analyst at the Congressional Research Service, says that after the next troop rotation this summer, "The reserves are pretty well shot." Experts say it's probably due to the strain of fighting a longer, bloodier war in Iraq than US commanders originally foresaw. The National Guard says it has about 86-thousand citizen soldiers available -- fewer than it has sent to Iraq over the past two years. The Guard has tripled re-enlistment bonuses. The Army Reserve has about 18 percent of its total troop strength available for deployment. Most Marine Corps Reserve troops have been mobilized at least once.