WASHINGTON, D.C.: General Ronald Fogleman, the Air Force Chief of Staff, asked for early retirement today, raising speculation that Defense Secretary William Cohen has decided to punish Air Force generals in connection with the Khobar Towers bombing. Fogleman, a highly decorated Vietnam War pilot and the 16th Air Force chief of staff, had said he would resign if Cohen held the generals accountable for failing to prevent the June 1996 terrorist blast which killed 19 U.S. airmen. Air Force officials said Fogleman's decision to resign was linked to the defense secretary's anticipated decision, which is expected later this week. Fogleman told his top staff he requested retirement for the good of the Air Force. If his petition is granted by Air Force Secretary Sheila Widnall, he would be the first chief of staff from the service to step down voluntarily before his four-year term expires.