But Gates did not rule out the possibility that the commander, Gen. Stanley A. McChrystal, might make such a request later. The report due after next week's Afghan national elections, however, is intended solely to assess conditions in the country and the effect of a new Obama administration security strategy. Any request for more troops 'will be considered separately and subsequent to his assessment,' Gates said. There has been speculation for weeks about whether McChrystal would ask for more troops and whether President Barack Obama would agree to bolster the force. Obama ordered 21,000 additional troops last spring to bring the U.S. force to 68,000 by the end of this year. In addition, about 30,000 international troops are deployed under NATO's command in Afghanistan. Some military officials believe more troops are needed if the United States and its NATO allies are to succeed in rolling back Taliban advances and protecting Afghan civilians. However, Gates said he is concerned that additional forces could fuel anti-U.S. sentiments, and he said finding new troops would be 'a challenge.' McChrystal is expected to call for an increasing focus on protecting the population and less on mounting individual attacks on extremists. Gates, briefing reporters Thursday at the Pentagon, said the security picture is 'mixed.' He said it is impossible to predict how quickly the country could be stabilized but reiterated his belief that 'we have to show progress over the course of the next year.' (Optional add end) Richard C. Holbrooke, the administration's special representative for Afghanistan and Pakistan, was pressed in a briefing a day earlier on how the administration would define success in the region. Holbrooke compared the determination to former Supreme Court Justice Potter Stewart's criterion for defining pornography: 'We'll know it when we see it.' At a session sponsored by the liberal Center for American Progress, Holbrooke also said that he preferred the term 'succeed' to 'win' because the Afghanistan war 'isn't going to end on the battleship Missouri,' a reference to the ceremony that ended World War II. Holbrooke is beginning a trip to the region today. 