SLIPPING AWAYBoy, that September deadline didn’t last long, did it?http://atrios.blogspot.com/2007_05_06_archive.html#400730378446039630[WP] U.S. commanders in Iraq are increasingly convinced that heightened troop levels, announced by President Bush in January, will need to last into the spring of 2008. The military has said it would assess in September how well its counterinsurgency strategy,