Iraq ? Insurgents targeted passenger buses north of Baghdad on Tuesday, as a suicide bomber killed at least eight people west of Mosul and gunmen seized 21 men traveling through Diyala province.

The latest bloodshed highlighted the slow-going, punch-counterpunch U.S.-led campaign against al-Qaida in Iraq, more than a month after Iraq’s prime minister said he expected the fight for Mosul would be a “decisive battle.”

The Americans view the northern campaign as a chance to subdue al-Qaida in Iraq in areas surrounding Mosul, a major transportation hub which the military has described as the terror group’s last urban stronghold.

Tuesday’s bombing, 40 miles west of Mosul, struck a bus heading from that city to the Syrian capital of Damascus.

Al-Qaida is believed to use the cover of sprawling sheep and produce markets in Mosul to smuggle foreign fighters, weapons and cash from Syria. Mosul, the country’s third-largest city, lies some 80 miles east of the Syrian border and 225 miles northwest of Baghdad.