WASHINGTON — The military plans to screen all troops who serve in Iraq and Afghanistan for post-traumatic stress and other combat-related health problems within three to six months after they return home, the Pentagon's chief health official said yesterday.

The Pentagon plans to spend nearly $100 million to make sure all returning troops take part in the program and get help if they need it, said Dr. William Winkenwerder Jr., the assistant secretary of defense for health affairs.

"At some point, we hope to touch everybody who's deployed who hasn't separated from the service," Winkenwerder said in testimony to the House Armed Services Subcommittee on Military Personnel.

Since at least the beginning of the Iraq war, service members routinely have been asked to complete a questionnaire before they come home that's designed to identify such problems as post-traumatic stress, depression and substance abuse. This would be the first time a follow-up survey was used to find problems from combat exposure that don't surface until weeks or months later.

The intent of the survey, Winkenwerder said, is to make sure troops are able to readjust in a healthful way.

"We literally want to reach out and say, 'How are you doing? How are things going? How are things at home? Is there anything we can do to help you?' " he said.

An Army study made public last week found that at least 10 percent of service members surveyed in Iraq last year reported experiencing post-traumatic stress or other mental problems.

A study reported last year in the New England Journal of Medicine found that 16 percent of all troops who served in Iraq and Afghanistan experience post-traumatic stress, severe depression or anxiety, but most didn't seek medical care for fear of being stigmatized.

Dr. Michael Kussman, the deputy undersecretary for health at the Department of Veterans Affairs, said 24,000 veterans from Iraq and Afghanistan had been diagnosed with mental-health problems due to combat experiences.

More than 14,000 have sought treatment at VA medical centers for mental disorders or drug and alcohol problems, he said.

Winkenwerder and Kussman said outreach was needed to let troops that these problems were normal and that it was OK to seek care.