board made up of government and civilian experts was given to "the washington post." the report doesn't accuse china of stealing entire designs, but if they didn't steal them, how did they compromise them? we spoke with a top security expert that did a report earlier on chinese military hackers. >> bits and pieces taken from many different sources, different laptops and computer systems that have been compromised. it is hard to take these pieces and gel them into one comprehensive picture of what might be being built or what the designs are. >> reporter: cnn couldn't independently verify the latest report findings. several members of the defense science board we contacted declined to speak to us. u.s. defense and other officials downplay the report, saying some of the information is dated, that they've taken steps to address the concerns. one saying, quote, the idea that somehow whoever the intruders were got the keys to the weapons kingdom is a stretch. but the pentagon has recently