Will there be another attack?

[Arthur Dent]

I'm sure they didn't expect to take many casualties targeting the Pentagon. It was the symbolism of attacking the heart of the US military machine

Pentagon wasn't the target. Analyisis of the jets flight path shows it was trying for either the Capital Dome or the White House. They missed the line-up and when they turned found themselves pointed at the Pentagon and went for it.

It's the general position of the experts that the terrorists new goal is maximum casualties and disruption of daily life for the purpose of creating terror.