President Hamid Karzai threatened Sunday to send troops to Pakistan to fight militants themselves.
Tuesday's deadly US incursion is under investigation, but it points up the contrast between the two nations' approaches to militants along the Afghanistan border.
Tehrik-e-Taliban carried out Sunday's bombing, the deadliest since the new Pakistani government took power in March. The suicide attack came two days after the militants freed the Pakistani ambassador to Afghanistan, Tariq Azizuddin.
The US is increasingly out of sync with Pakistan's newly-elected government, say analysts.
The latest, at a naval college in Lahore Tuesday, was the fourth in five days.
Attacks aren't just a US concern, more Pakistanis say.
The president cast himself as Pakistan's best bet for stability in a nine-day visit.