U.S. reports April is this year's deadliest month in Iraq

~ Al-Zawahri issues new video saying suicide bombings have "broken the back" of the U.S. military.

BAGHDAD, Iraq -- An American soldier was killed in a roadside bombing north of Baghdad, the U.S. military said Friday, making April the deadliest month for American forces in Iraq this year.

Al-Qaida's No. 2 leader issued a video saying that hundreds of suicide bombings in Iraq have "broken the back" of the U.S. military -- the latest in a volley of messages by the terror network's most prominent figures.

Ayman al-Zawahri, an Egyptian militant believed to be hiding in Afghanistan or Pakistan, said that U.S. and British forces had bogged down in Iraq and "have achieved nothing but loss, disaster and misfortune."

American troops, acting on tips from Iraqi intelligence, meanwhile, killed the reputed al-Qaida boss of Samarra, where a Shiite shrine bombing two months ago nearly plunged the country into civil war.

The latest American death, which occurred Thursday evening, brought the number of U.S. troops who have died this month in Iraq to at least 69.

Although that figure is well below some of the bloodiest months of the Iraq conflict, it marks a sharp increase over March, when 31 American service members were killed. January's death toll stood at 62 and February's at 55. In December 2005, 68 Americans died.

Reasons behind the rising U.S. deaths were unclear, and U.S. military officials have cautioned not to interpret cyclical changes as the beginning of a trend.