sentences:  Motives for attacks against Iraqi refugees are unclear, but may be due to antagonism towards Shia generally, because of their sectarian association with the government, or because Iraq's Shiite-led government is perceived as siding with Assad.Though Baghdad has publicly vowed not to become involved with Syria's war, skeptics believe it is at least helping Iran ship weapons and reinforcements to Assad's government.In March, the US urged Baghdad to cut off its airspace to flights headed to Syria from Iran, and Iraqi Prime Minister Nouri al-Maliki pledged to curb arms smuggling across his borders into Syria.