More Right wing ignore facts and make crap up.
Infowars doesn't lay out truth- NO Norwegian source quotes an Erick Haugland. The use of Nettavisen is bogus- they just say there are many refugees coming into the country. This is just a rant repeated over and over again by the CON artists with blogs.
Now about the shooters the OP mentions-
Maj. Hasan was BORN in this country.
Boston bombers came here as minors.
San Bernadino has merit, except the means to screen for their social media posts was part of the anti-gubmint heated rhetoric many felt was unconstitutional.
But let's not be so narrow- the FBI missed 19 (or 20) Muslims training on how to fly planes once off the ground, and Timothy McVeigh killed 168 or 169 people in OKC without ever raising an alert.
To continue-
Jared Lee Loughner- long history of mental issues and drug abuse- his former friends noted his hatred of women in positions of power (did nothing) and Jared legally purchased a hand gun
James Eagan Holmes- Professional health care workers suspected he was a danger but did nothing
Adam Lanza- long history of mental health issues
Christopher Harper-Mercer white supremacist with long history of mental health issues.
Dylann Roof- lots of social media hate posts, white supremacist, drug abuse
Elliot Roger- long history of mental issues and social media postings
That is just the tip of the mass murderers in America iceberg. While it is easy for some to select a narrow segment to call scum- we face a much bigger issue when it comes to 'see something-say something'....
eace