how to explain my 8yrs old

My son 8years old is asking me questions I have difficulty explaining.
Q. Who is Bin Laden and why he was killed by Americans?
I said he was muslim and he planned and destroyed WTC twin towers.

Q. By sitting in Afghanistan caves?
I said I think so. Planning can be done and he supplied resources like money etc.

Q. His men who did it were Americans?
I said yes. Few were Americans.

Q. So Bin Laden planned to destroy WTC towers with the help of few muslims. How did they do it?

A. They breached airport securities, set in the plane, took control of the plane and crashed to building; its known as 9/11.

Q. But there were 2 buildings?
A. Yes, from the 2 different airports to 2 different planes at the interval of 5minutes they did it.

Wow he exclaimed! Cool plan. I was not born but he must be genius to dodge Americans securities, took control of the planes and bang.

Q. Were they airline pilots? To crash a plane exactly in the towers need skill.
A. Thats what happened.

Q. And it took them 10years to catch him.
A. Thats what happened.

Q. I would not blame him. I blame Americans not able to secure their country.

What shall I say ?