BAGHDAD (AP) – The U.S. military in Iraq says a joint mission by American and Iraqi troops has killed or arrested six suspected Al Qaeda leaders accused of running an extortion and assassination ring in the north of the country.

A U.S. military statement late Thursday said the operation was carried out from March 18-24 in Mosul, 225 miles (360 kilometers) northwest of Baghdad.

It says the network helped fund Al Qaeda in northern Iraq by targeting oil companies and small businesses for extortion.

The statement added that the ability of Al Qaeda in Iraq to operate and restructure will be “severely hindered” because of the operation.