BAGHDAD, Iraq, Feb. 8 — American officials here have obtained a detailed proposal that they conclude was written by an operative in Iraq to senior leaders of Al Qaeda, asking for help to wage a "sectarian war" in Iraq in the next months. The Americans say they believe that Abu Musab al-Zarqawi, a Jordanian who has long been under scrutiny by the United States for suspected ties to Al Qaeda, wrote the undated 17-page document. Mr. Zarqawi is believed to be operating here in Iraq. The document was made available to The New York Times on Sunday, with an accompanying...