sentences:  In December 2007, "The Washington Post"'s "Fact Checker" stated that "While some of Petraeus's statistics are open to challenge, his claims about a general reduction in violence have been borne out over subsequent months.It now looks as if Petraeus was broadly right on this issue at least".Michael E. O'Hanlon and Jason H. Campbell of the non-partisan Brookings Institution stated in January 2008 that Iraq's security environment had reached its best levels since early 2004 and credited Petraeus' strategy for the improvement.