Mullen has in the past called the military fight in Afghanistan under-resourced in both personnel and equipment. He has said that if the security situation in Iraq continues to improve, a drawdown of troops there could enable him to send additional troops to Afghanistan.
The greatest need has always been for 3,000 military trainers to help prepare Afghan police, but military commanders in Afghanistan have also said they would like an additional two combat brigades, or the equivalent of 7,000 more troops.
While this weekend's deadly attack is a rare case in which Taliban militants have taken a U.S. military force head-on, they are increasingly shifting to more tactics used in Iraq by insurgents, in particular roadside bombs.
The Pentagon has already sent more than 800 of the large vehicles known as Mine Resistant Ambush Protection vehicles, or MRAPs, to Afghanistan to help counter the growing use of roadside bombs. Mullen is reviewing a new request from commanders in Afghanistan for an unspecified number of even more of the vehicles.