I've posted a longer question on this before but it was put on hold. I thought that it may help if I just ask a more concrete and a general question regarding this issue.
I was wondering if a Schengen country can advise the United States to revoke a valid visa if they discover inconsistencies in an applicant's file. Actually, I was reading on a popular forum in Nigeria about some applicant's experience where a Schengen country (Germany) literally forwarded his file to the US embassy so they can cancel his visa. He also gave me a link in which a popular Nigerian singer got his US visa cancelled thanks to the Germans. This is the link http://www.modernghana.com/movie/332/i-lost-n20m-yinka-ayefele-gospel-singer.html
Now I'm quiet confused after reading this. I know that many country's have information sharing agreements and I'm aware of such agreements between the UK, Canada, US, Australia, etc. But, I haven't came across a similar agreement between Schengen countries and the US. But here is my bigger question.
Every time someone from the "third world" applies for a Schengen visa and if he/she is in possession of a valid US visa, is that person also risking his US visa while they're applying for the Schnegen visa? Can the Schengen countries just forward your file to the US embassy for visa cancellation without any hindrance if they "suspect" something is wrong with your application?