I found this article on Yemen
Here’s an excerpt…2016 Washington Post
"They took advantage of the political and security vacuum that emerged from the 2011 revolution here — part of the Arab Spring uprisings — that toppled longtime autocrat Ali Abdullah Saleh. By the fall of 2014, the Houthis had swept southward and occupied Sanaa. They forced Saleh’s successor, U.S.- and Western-backed Abed Rabbo Mansour Hadi, to resign last year. Soon after, the anti-American slogans emerged throughout the city.
On one level, the anger is an extension of the Houthis’ credos. Their flag reads: “God is Great, Death to America, Death to Israel, Curse on the Jews, Victory to Islam.”"
Even Feudal Lords knew to build a wall to keep out enemies who wanted to kill the people. No one is objecting to immigrants, but let’s vet them first. And I know people say they are vetted, two years. I don’t have proof but I’m thinking some people got through… Like San Bernadino’s terrorist’s fiancee…