Top US military leaders are expected soon to recommend to Defense Secretary Robert Gates hundreds of US troops who could be sent to Afghanistan during the next month or so, according to a senior military official. The units are likely to be small and could include engineers, ordnance disposal troops and other support forces needed to shore up fighting units and the training of Afghan forces. Officials have not ruled out identifying a larger, brigade-sized unit before the end of the year that could either be shifted to Afghanistan from a planned deployment to Iraq or moved from some other location. US commanders in Afghanistan have been asking for three combat brigades, or roughly 10,000 more troops, to help quash rising violence there. The senior official, who requested anonymity because the proposals are not public, said the recommendations have not been approved by Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, or delivered to Gates.