Well, we discovered that we needed to upgrade security so that potential criminals weren't coming into our country, and so potentially harmful substances weren't being brought onto our planes. That meant literally anything that could become a bomb, start a fire, stab someone etc. As for Pearl Harbour, I think that had more of an affect on how we thought our military and defence system was working.
After shortly returning to Medina, Muhammad fell sick with an illness, that ultimately caused him to die.
Answer: cargo ships
Explanation: I took the test on k12 Hope this helps
