Answer:
It shaped American foreign policy in the Middle East during his presidency.
Explanation:
9/11 caused the War in Afghanistan and made Bush declare a "war on terror". Conflicts part of the War on Terror would begin under his administration. For example, the Iraq War (which took up a good part of his presidency) is also considered part of the War on Terror. Overall, 9/11 and the War on Terror would make a foreign policy shaped around the idea of containing extremism during the Bush years.