White House national security adviser Stephen Hadley on Thursday said that the murder of former Pakistani prime minister Benazir Bhutto will likely be a topic of discussion during President Bush's nine-day trip to the Middle East beginning next week.

Bush has long cast his Global War on Terror as one big, global contest between moderation and extremism. In this view, Bhutto's December 27 assassination was a victory for the extremists, and thus related to tensions in the Middle East.

Challenged on whether al Qaida or related terrorist groups killed Bhutto, as the Pakistan government alleges, Hadley acknowledged, "We don't know." Many in Pakistan suspect involvement, or at least complicity, by elements of the government of Pakistani President Pervez Musharraf, who Bush yesterday again called an "ally." There's no proof of Pakistani government involvement, but some U.S. officials don't necessarily buy Musharraf's explanation of the killing, either.

Bhutto's murder and the continued instability in Pakistan could have a quite different effect on Bush's trip to Israel, the Palestinian areas, the Persian Gulf and Egypt. Along with the 2008 presidential campaign, violence in Kenya and other world events, it could overshadow a trip by a president who is in his final year in office and is not expected to make dramatic news.