Washington ? For the second time since the Iraq war began, the Pentagon is replacing body armor for U.S. troops in Afghanistan and Iraq, citing a need for better protection that can withstand the strongest of attacks from insurgents, a spokesman said Saturday.

The effort, which began more than a year ago, would upgrade the protection used by more than 500,000 soldiers as well as civilian employees and reporters. The first upgrade installed ceramic protective plates in the vests and was completed in 2004.

Defense officials acknowledge the replacement processes have been slowed in part by debates over what is best for the troops. The current replacement is expected to take several months to complete, said an Army official, who requested anonymity because of the sensitivity of information affecting troop safety.