Pakistan has endured a particularly grisly week. Since Feb. 13, about 100 people have been killed in at least five attacks across Pakistan's four provinces and the Federally Administered Tribal Areas, highlighting the threat of violent extremism that continues to afflict the country.

Revenge is likely the driving force behind the spate of attacks. The Pakistani army has been targeting militant groups since it launched the Zarb-e-Azb campaign in June 2014. As more militants have been swept up in the operation, reprisal attacks have ensued. Soft non-military targets outside the tribal areas provide the easiest prey.

In the bloodiest attack of the week — and the deadliest act of terrorism in Pakistan in two years — a suicide bomber targeted a crowd of Sufi devotees Feb. 16 at a shrine in Sindh province. The Islamic State claimed responsibility for the bombing, which killed at least 83 people. That attack followed a suicide bombing Feb. 13 in a suburb of Peshawar that killed the driver of a vehicle and injured its passengers, a group of three judges. Two days later, a suicide blast outside the assembly house in Punjab targeted a crowd of pharmacists protesting government regulations, leaving 13 dead. Jamaat-ul-Ahrar, a breakaway faction of the Tehrik-i-Taliban militant group, claimed the attack.

In response to the Sindh bombing, the Pakistani army launched a nationwide offensive, killing about 100 militants. The army also closed the Torkham crossing on the Afghanistan border. Closing the crossing, the busiest transit and trade point between the countries, is a form of economic punishment for landlocked Afghanistan. Pakistan has long accused its neighbor of allowing militants to find sanctuary there. Previous closings of Torkham have lasted as long as two weeks.