After the American invasion of Afghanistan, al-Masri went to Iraq via the United Arab Emirates in 2002, according to the subsequent account given by his widow. He lived initially in Baghdad's Karrada, then in the Amiriya fainal, and then al-Jadida, where he took charge of al-Qaeda's operations in the southern part of the country. The United States military said that Masri "helped draw other insurgent groups into al-Qaeda’s fold." "DefenseLINK News" reported that Masri "helped establish the Baghdad cell of al-Qaeda in early 2003". Soon after, he "worked the ‘rat line’ down the Euphrates River Valley supplying suicide bombers via Syria." After the US-led invasion, the family left Baghdad for Diyala to the north. Hasna related "The two-storey house where we were was hit in a US air raid. Then, one of the men was killed but my husband and I were able to escape to Fallujah" [the Sunni Arab town west of Baghdad that was at the time a bastion of the anti-US insurgency]. al-Masri participated in the major 2004 battle of Fallujah. After US troops stormed the town in November 2004, the family moved again, this time to the town of Abu Ghraib, on the western outskirts of the capital. In 2007, al-Masri and his family moved to the Lake Tharthar area. "We were changing houses the whole time, right up to his death," claimed Hasna.