A car bombing aimed at Pakistani soldiers in the country's northwest killed at least 41 people Monday, officials said, in the fourth suicide attack in little more than a week.

Pakistan is reeling from the attacks, which have hit the country's military headquarters, a U.N. office in Islamabad, a crowded urban market and most recently a rural military patrol, killing nearly 120 people since Oct. 5. The strikes follow a relatively quiet summer and underscore the threat posed by Islamist militants, despite military efforts against...