Insurgents fired four mortar shells at Baghdad's heavily fortified Green Zone on Tuesday, killing two civilians, on the same day Vice President Joe Biden arrived in the Iraqi capital on an unannounced visit to help resolve political differences among Iraqis.
The shells were fired after Biden arrived in Iraq on his third trip to the country this year. It was not clear where he was at the time.
The faint pops of the mortars being fired were audible on the opposite side of the Tigris River from the Green Zone, and at least one of the shells was heard exploding on impact.
One round that fell short hit residential apartments on the Tigris River, killing two people and wounding five others, including a 12-year-old, a police official said. He spoke on condition of anonymity because he was not authorized to comment to the press.
As the White House's point man on Iraq, Biden said he has been in regular contact with the country's leaders.
"The whole purpose is to see how we can be helpful, if we can, in helping them resolve the outstanding political issues they have to resolve internally, so that when the (security agreement) is fully implemented we leave a stable Iraq," he told reporters after meeting with Gen. Ray Odierno, the top U.S. commander in Iraq, and U.S. Ambassador Christopher Hill.
The U.S.-Iraqi security agreement calls for the withdrawal of American combat forces by the end of August, 2010 and of all U.S. troops by the end of 2011.
The three-day trip gives Biden a chance to meet with the full range of Iraqi leaders, both in Baghdad's central government and in the self-governing Kurdish region, whose boundaries with the rest of the country have become a volatile fault line.
"I'm here to listen, and occasionally they have asked me to be an interlocutor on their behalf, and it's been of some value so far," he said.
Biden said that Odierno was optimistic that the readiness of Iraqi forces would allow the U.S. military to withdraw all combat forces next year according to plan, and then proceed with pulling out the remaining 50,000 troops by the end of the following year. There are now about 130,000 U.S. troops in Iraq.
The Iraqi government plans to hold a national referendum on the agreement in conjunction with elections in January. If approved, the referendum would require all U.S. forces to leave within one year -- well ahead of the existing plan to withdraw completely by the end of 2011.
Biden said of the referendum that Iraqi leaders have indicated "it is likely to happen." But he added, "I'm not sure it's settled yet."