A suicide bomber killed at least 41 people in an attack on the Pakistani military near Swat on Monday as the Taliban claimed responsibility for a weekend raid on the army’s headquarters.

The bombing was the fourth significant assault in a week, after attacks on Islamabad, Peshawar and Rawalpindi. The raids are part of an apparent campaign to deter a planned army offensive against Taliban strongholds in the Waziristan region along the Afghan border.