This is weird. An Israeli and a British cryptographer were both denied entry into the US. One of them is evidently pretty famous (helped create RSA).

Still trying to wrap my head around the "why", but it sure seems spoopy.

Why Are Cryptographers Being Denied Entry into the US?

In March, Adi Shamir – that's the "S" in RSA – was denied a US visa to attend the RSA Conference. He's Israeli.

This month, British citizen Ross Anderson couldn't attend an awards ceremony in DC because of visa issues. (You can listen to his recorded acceptance speech.) I've heard of two other prominent cryptographers who are in the same boat. Is there some cryptographer blacklist? Is something else going on? A lot of us would like to know.

Sauce

https://www.schneier.com/blog/archives/2019/05/why_are_cryptog.html