BAGHDAD, Iraq – April was the deadliest month for U.S. military forces in Iraq in nearly a year and a half and the worst by far for American troops since they officially ended combat missions in the country last year, according to military and independent record keepers.

In a statement released here Saturday, U.S. forces said an 11th soldier died Friday while conducting an operation in southern Iraq. With that death, the U.S. military tied its highest body count in Iraq since November 2009, when 11 soldiers also died, according to the website icasualties.org.

Five of the deaths were attributed to bombings and mortar or other attacks, mostly in the majority-Shiite south. Six were classified as noncombat-related.

The spike comes as U.S. officials are urging Iraqi leaders to decide soon whether they want some American troops to stay beyond a year-end deadline for their withdrawal.

It also coincides with threats by Shiite cleric Moqtada al-Sadr to reconstitute his Mahdi Army militia if the Americans do not leave.

Some U.S. service members say they have sensed a surge in mortar attacks on U.S. bases in the south amid the mounting political pressure in Baghdad for a decision on the deadline.

Last week, warning sirens sounded on the U.S. base in the southern port city of Basra when mortar fire struck the airfield, not far from the building that is expected to be turned over to the State Department later this year for use as a consulate.

Iraqi Prime Minister Nouri al-Maliki has said that Iraqi forces are capable of managing the country’s security and that it will not be necessary for U.S. troops to stay. But after the Sunni parliament speaker said last week that the legislature might debate reaching a decision of its own, Maliki said he would hold multiparty discussions on the issue when he returns from a trade mission next week.

According to an Associated Press tally, Friday’s death brought to at least 4,452 the number of U.S. military personnel who have died in Iraq since the war began in March 2003.