Answer:
They wanted to make a political statement about American support for Israel
Step-by-step explanation:
Al-Qaeda was the biggest villain in the world until recently, operating in the Middle East, but also having lot of affiliations in other regions like Africa, Southeast Asia, Caucasus, the Balkans. It was the largest terrorist organization, having extreme Islamic beliefs as its basis and core. It was a terrorist organization that waged wars and supported other terrorist organizations against Israel and the West, especially the United States. Because of the support of the United States for Israel, and all the tensions and hatred toward this nation from al-Qaeda, the attacked on American soil, using planes to take down very important buildings. This was done in order to show the United States that they are vulnerable, and that they should not interfere in the Middle East.