BAGHDAD, Iraq - U.S. soldiers have captured a former Saddam Hussein regime spy, the U.S. military said, and a suicide bomber attacked the main checkpoint to Baghdad International Airport today, wounding at least seven Iraqis, police said.

The explosion sent a huge cloud of black smoke billowing into the sky, destroyed several vehicles and underscored the difficulties U.S. and Iraqi authorities are facing to curb the rampant insurgency.

In New York, Iraqi Foreign Minister Hoshyar Zebari said U.S.-led forces must remain in Iraq until the country's own soldiers and police can take responsibility for securing the nation amid its continuing insurgency.

U.S. soldiers struck a blow against militants plotting attacks by capturing four wanted terrorists during separate raids since Sunday, including a former spy in Saddam's secret service who was believed to be financing several terrorist groups in western Baghdad's Ghazaliyah district, the military said in a statement today.