A California congressman wants the Defense Department to step up its efforts to fight child abuse and child rape in Afghanistan, saying it poses "a direct threat to U.S. service personnel."

Republican Rep. Duncan Hunter, who served with the Marine Corps in both Iraq and Afghanistan, sent a letter to Defense Secretary Ash Carter on Monday asking for more aggressive steps to deal with the problem after recent reports that Taliban forces are using child sex slaves to infiltrate Afghan security forces and carry out deadly attacks.

"It is my belief that we can begin taking immediate steps to stop child rape from occurring in the presence of U.S. forces and reduce any risk of coinciding insider attacks," he wrote. "This includes imposing a zero-tolerance policy and ensuring service personnel are not discouraged from reporting cases."

In February, the Pentagon's inspector general launched an investigation into how U.S. troops handle allegations that Afghan military and police leaders are sexually abusing children, a widespread problem known as "bacha bazi" in the country.

Hunter and other lawmakers have long complained that too many commanders turn a blind eye to the practice in an effort to hold onto support from the still-unsettled security forces.

Earlier this year, Army officials moved to dismiss Sgt. 1st Class Charles Martland from the service after reports the Green Beret assaulted an Afghan local police officer in 2011 for raping a young boy and attacking his mother for reporting the crime.

Lawmakers intervened, and in April the Army reversed the decision. Since then Hunter and his colleagues have publicly questioned the military's and administration's commitment to human rights.

In his letter, Hunter referenced the Martland case and said military officials need to use the latest insider attacks "to send a signal that child rape will not be tolerated."

Defense officials are awaiting results of the inspector general investigation and a separate report from the office of the Special Inspector General for Afghanistan Reconstruction.

Leo Shane III covers Congress, Veterans Affairs and the White House for Military Times. He can be reached at lshane@militarytimes.com.