It takes two years of vetting before a refugee is granted entry to the United States, and even then most applicants are denied. The process includes multiple interviews, background checks, and biometric searches.[1]
Why isn't this sufficient? Well, it is sufficient. Your chances of being killed by a refugee turned terrorist is 1 in 3.6 billion according to the Cato Institute.[2] So why isn't considered sufficient? Quite frankly it a political ploy to gain support by stoking unfounded fears of others.
Germany had a massive amount of sexual assaults perpetrated over NYE last year, mainly from Middle Eastern immigrants/refugees. Things like this tend to leave lasting bad impressions on refugees in general, regardless of how true it is, and look at how that issue blew up in Merkel's face since then.
The offenders were mostly from northern Africa (so not from Syria, where most immigrants in 2015 came from). That Washington Post article is clearly biased. Better read the source article: http://www.sueddeutsche.de/politik/uebergriffe-in-koeln-frau...
Why isn't this sufficient? Well, it is sufficient. Your chances of being killed by a refugee turned terrorist is 1 in 3.6 billion according to the Cato Institute.[2] So why isn't considered sufficient? Quite frankly it a political ploy to gain support by stoking unfounded fears of others.
[1] https://www.nytimes.com/interactive/2015/11/20/us/why-it-tak...
[2] https://www.cato.org/publications/commentary/truth-about-for...