Edit: Moreover, the Orlando and San Bernadino attacks were carried out by American citizens who were radicalized online. No amount of travel bans would have prevented those attacks or prevent future attacks by home-grown terrorists

it's just part and parcel of living in America in current year!

A lot of the religious extremism that's led to terrorist attacks in the US, UK and Europe have been from the children of Middle Eastern immigrants. Omar Mateen's father immigrated here in the 1980s, shortly before his son was born. The influence his father had on his son's life was obviously very significant, as he was a closeted homosexual who believed he had betrayed his faith based on his sexual attractions. Syed Farook's parents were Pakistani immigrants in the 80s. Tashfeen Malik was born in Pakistan but lived most of her life in Saudi Arabia before immigrating to Southern California. You can make an good case for an argument that a large majority of recent Middle Eastern refugees have not led to a significant amount of terrorist attacks in the country, you can't really say that blocking a regional group from entering the US will have no effect on future attacks. That's false. The 9/11 hijackers were not American born citizens.