The assault "could be any day," according to an unnamed senior Pakistani official.
On early Tuesday, the Pakistani government launched airstrikes in the the mountainous Shawal region between North and South Waziristan that killed approximately 30 people.
The Pakistani government undertook Tuesday airstrikes and was planning its major military operation following the execution of 23 captured Frontier Corps militiamen by the Taliban on February 16. Over the past five months, Pakistani officials estimate 460 people have been killed in militant violence.
Taliban attacks have delayed plans to continue peace talks between the government and Pakistani Taliban.