Efforts to reduce the number of American troops in Iraq are being adjusted to handle a growing security problem in the northern part of the country where civil war between Arabs and Kurds is at risk of breaking out. U.S. ArmyGeneral Ray Odierno announced in Baghdad on Monday that several thousand soldiers will be deployed for the first time to a section of Iraq’s oil-rich north where Kurds and Iraqis cannot agree on the location of the border, and thus how much petroleum each side controls. American combat troops will form joint units with Iraqi security forces to try to keep the peace in areas around the cities of Mosul and Kirkuk.