How well would the Burj Khalifa or the new WTC1 stand up to an attack like 9/11?

Factual Questions
1

I know the World Trade Centers were built to withstand an impact from a passenger jet, but a number of things went wrong that day, from the fire retardant coming off to the jet being much larger and going much faster than anticipated.

I’m wondering if we’ve learned anything vital from the 9/11 attacks, possibly enough to stave off the collapse of a building in similar circumstances. If so, is the new WTC being designed in such a way, or the largest building on earth? Or would virtually any type of building come down from such a strike and it’s almost impossible to design against?

2

Bill Baker, the lead structural engineer on the burj, gave a presentation at my alma mater. He addressed this and basically said that it can’t be designed against. You can delay, and make evacuation safer, but you can’t build a skyscraper with current technology and budgets to withstand that sort of thing.