There are two types of immigrants: legal and illegal. On the one hand we are told that illegal terrorists are streaming across our southern border among the illegal Hispanics; on the other hand we are told that there a loads of legal immigrants streaming into the country concealed among peaceful immigrants. Of course there are also terrorists that must be coming into the country. Where are all these terrorists?
Shootings The New Town, CT, school shooter and the Aurora, CO, theater shooter were both non-Muslim Americans. Going further back, the Columbine, CO, shooters were the same. The 2014 Ft. Hood shooter (Ivan Lopaz) was born in Puerto Rico so was also an American citizen and wasn't a Muslim. No immigrant or illegal terrorists there. The VPI shooter(Seung-Hui Cho), a South Korean citizen and not a Muslim. He was on a permanent visa and was the only foreign, non-American citizen among the group.
The 2009 Ft. Hood shooter (Major Malik Hasan) was an American born psychiatrist and Muslim born to Palestinian parents. He had several brothers, all but one of them have moved to Jerusalem. The Orlando nightclub shooter (Omar Mateen) was American born to "moderate Muslim" parents. His father immigrated from Afghanistan in the 1980s. There are questions as to whether Mateen's massacre was a terrorist attack. Though both of these were Muslims, neither was an immigrant, legal or illegal. This brings us to the San Bernardino, CA, shooters (Sued Farook and his wife Tashfeen Malik), where the husband was American born of Pakistani descent and Malik was born to Pakistani parents but lived in Saudi Arabia. She is the sole Muslim immigrant on a visa, therefore legal, but not a U.S. Citizen.
Bombings The major successful bombing was, of course, that of Oklahoma City, OK, by the duo of Timothy McVeigh and Terry Nichols, with many more deaths (168) than any of the shootings. Their motive seems to have been to avenge the Ruby Ridge standoff and the Waco David Koresh cult fire. There are the Boston Bombers, too, the Muslim, Chechen Tsarnaev brothers (Tamerian and his younger brother Dzhokhar who became a naturalized U.S. citizen in 2012.). They originally entered the U.S. legally with their parents seeking political asylum. U.S. authorities were warned about the older brother twice.
What about the non-successful terrorists? The failed Times Square Bomber (Faisal Shahzad) was a naturalized Pakistani-American citizen. The failed Shoe Bomber (Richard Reid) was a Brit who had converted to Islam while in jail and tried to set off a bomb on an American airlines flight from Paris to Miami. The Underwear Bomber (Umar Mutaliab) was from Nigeria and has a Nigerian father and Yemeni mother. He tried to set off a bomb on a Northwest Airlines flight from Amsterdam to Detroit.
Domestic Airlines Even the 9/11 airplane hijacker terrorists were in the U.S. on legal visas, and none had come "streaming" across of southern border or from Canada, or by stealth boat.
I see no evidence of of terrorists streaming across our southern border, perhaps because of easier ways of entering the U.S. Of the mass shootings, al were American born except for tow , one of which was a Muslim. So far, at least, there is no evidence of a large number of people coming into the the U.S. legally or illegally to commit terrorist or other deadly acts. Certainly as the CIA Chief, John Brennan has said,
"To compensate for territorial losses, ISIL will probably rely more on guerrilla tactics, including high-profile attacks outside territory it holds," Brennan said. "A steady stream of attacks in Baghdad and Damascus demonstrates the group's ability to penetrate deep inside enemy strongholds." We must be vigilant, but there is no need to panic as some politicians would have us do.