Kirkuk is the latest part of Iraq to feel the effects of an upturn in violence. The strongly Kurdish city was rocked by a truck bomb on Tuesday which killed at least three people and injured nearly 60 others when it exploded outside a police station.
The Iraqi government is fighting al-Qaeda linked militants of the Islamic State of Iraq and the Levant, or ISIL. They have taken control of much of Anbar province and two cities, Fallujah and Ramadi.
An overnight air-strike and offensive failed to recapture Ramadi, but the Iraqi army claimed at least 25 militants had been killed when a weapons convoy was hit with air-to-ground missiles in a town square.
The US has ruled out sending any troops back to Iraq to help the government, but it is supplying material support and selling Baghdad equipment and weapons, speeding up delivery to drive the offensive against the ISIL.
The fear is if unchecked the ISIL might succeed in igniting tit-for-tat sectarian killing from which it could be hard to pull back.